Search

Natural stones used in monuments have to deal sooner or later with weathering. The desire to preserve cultural heritage created a wide variety of products to reduce the rate of stone decay and to strengthen decayed stone. The ability of these water repellents and consolidants to penetrate inside natural building stones is one of the main factors controlling their performance. The determination of this penetration depth is crucial for the application of conservation products. Because the impregnation depth also depends on the characteristics of the material itself, such as total porosity and pore size distribution, these should be considered when restoration is planned. X-ray micro-computed tomography (μCT) was used to determine the impregnation depth of water repellents and consolidants. 3D information about the total porosity and the pore size distribution was obtained with the combination of μCT and home-made 3D software. This experiment should provide a basic step for extra advice on the suitability of products for the treatment of a particular rock type.

The Lede stone (Lutetian, Eocene) is an important historic building stone used in the NW of Belgium. In Ghent, it is dominant in the post-Romanesque built cultural heritage. Its use was restricted several times by socio-economic constraints. Since quarrying and production started to cease from the seventeenth century, periodic revivals favoured the use of Lede stone for new buildings and restoration projects. Sulphation is the main threat for the Lede stone as black crusts are the most common degradation phenomena on this arenaceous limestone. Around the turn of the nineteenth century, the Belgian Gobertange stone was the most widely used replacement material. Throughout the twentieth century, the use of replacement material shifted towards French limestones. However, their colour, texture and petrophysical properties differ from the Lede stone, for which a natural yellow-brown patina is very characteristic. In order to solve this mainly aesthetic issue, several new stone types are used as replacement stone in the twenty-first century, while many others have been suggested. It remains, however, difficult to find a replacement stone that matches the visual and petrophysical properties of the Lede stone. One remaining Lede stone quarry pit has increased its activity since 2011, offering the opportunity to use new Lede stone as replacement stone.

Basaltic eruptions have been observed to produce structurally complex, compound 'a'? lava flow fields but their mor- phometry has only rarely been systematically documented. We document the morphology and structures that developed during the emplacement of the 1982 basaltic lava flow field at Mount Cameroon (MC) volcano over a period of one month. Topographic cross-sections (13 in total) were made from the main vent (~2700 m above sea level (a.s.l)) down to a distance of 5.5 km on the cooled lava surface. Details obtained from these cross-sections include: channel width and depth, levee slope, lava surface morphology and structures. These details enabled us to describe the physical char- acteristics of the 1982 lava flow field. The inclined (12° - 19°) underlying slopes on which this flow field was emplaced resulted in a characteristic channelized basaltic 'a'? flow field morphology. This includes a proximal zone characterised by reduced flow width and depth with no subsidiary channels. Slab-crusted lava dominates the proximal channel dis- tinctively bent into convex upward shapes. 7 secondary vents were observed for the first time ~2.5 km from the main vent, with heights of 3 - 15 m. This is a very significant observation since it points to the fact that the flow field em- placement may have been a product of 2 eruption sites as observed at other historical MC lava flow fields. This suppo- sition was ruled out by further evidence obtained from other surface features within the flow field. The presence of these secondary vents still has an important bearing in lava flow hazard assessment. Field observations also revealed the presence of tumulus. This is a novel feature for MC lava flow fields. It displayed a close similarity to those observed at other basaltic volcanoes occurring in association with clinker 'a'? lava, lava tubes, squeeze-ups and pressure ridges. Channels are well-defined, bounded by levees. Accretional and overflow levees dominate in this flow field. This lava flow-field attained a final length of 7.5 km, an area of 2.6 × 106 m2 and volume of 1.3 × 107 m3. The presence of tumu-lus indicates internal inflation together with structures such as pressure ridges and squeeze-ups which are also attributed to compressive forces. Our observations suggest that real-time monitoring of compound lava flow fields evolution at MC may reveal the emplacement mechanisms of complex structures such as the secondary vents (~2180 - 2011 m a.s.l.) observed within the flow field. In addition, documenting the occurrence, morphology and link between lava tubes, tu- mulus and squeeze-ups may allow us to determine the risk of reactivation of a stalled flow front. This will thereby en- hance the ability to track and assess hazards posed by lava flow emplacement from MC-like volcanoes.

As for many other effusive volcanoes, Mount Cameroon (MC) is a volcano for which only limited information exists on lava flow properties and emplacement dynamics for recent eruptions. This study provides new quantitative constraints for rheological and dynamic characteristics of lava flow effusion for the 1982 and 2000 eruptive events, used to calibrate the FLOWGO thermo-rheological model for these lava flows. The FLOWGO 1-D physical model is used to simulate down-flow evolution of the geometry and rheology of channel-contained cooling-limited lava flows. Morphometric data from historical lava flows were acquired from the field, e.g. channel geometry, levee and background slope, in order to estimate lava yield strength, velocity and effusion rate. Lava density and viscosity were also estimated from compositional data and laboratory methods. To account for uncertainty in the input rheological and geometrical data, three end-member scenarios were used to bracket the potential range in lava channel initial dimension, initial lava temperature and phenocryst content. For each of these scenarios, two crustal growth models were used: one assuming strong insulation due to lava flow surface crusting, the other a much lower crusting rate. Twelve numerical simulations were made per flow and the results were compared against the channel geometry, microlite content, yield strength and viscosity estimates from field and laboratory investigations. Best-fit models where obtained for both the 1982 and 2000 lava flows using a low rate of surface crusting, high initial temperature and low phenocryst content. Model-predicted lengths were within 5% of the actual lengths. Modelled mean effusion rates for the 1982 (52-64 m3 s?1) and 2000 (10 m3 s?1) flows closely matched field data derived estimations (26-68 and 9.5 m3 s?1 respectively). FLOWGO model results are highly sensitive to initial channel dimensions, phenocryst content and the FLOWGO model is unable to reproduce the observed rapid near-vent increase in microlite content. Near-vent rapid cooling induced by lava degassing is yet to be fully documented and integrated into numerical lava flow models such as FLOWGO, but obtained results already provide valuable insights for lava flow hazard assessment at Mount Cameroon.

Dalle de verre windows, created from 19301940 onwards, consist of glass pieces with a thickness of approximately 2 to 5 cm, set in a matrix of (reinforced) concrete. Besides the degradation of the concrete, the windows suffer mainly from a complex three-dimensional form of cracking of the glass elements. The cracks need to be consolidated in order to ensure stability and improve transparency. A selection of possible adhesives was evaluated: Araldite® 2020, Hxtal NYL-1, Fynebond, Paraloid® B-72, LV740, A18 and OR-G®. An attempt has been made to objectively compare these adhesives using a bench-marking system. None of the adhesives appears to be suitable for in situ application; sufficient penetration of the adhesives can only be realised with the help of vacuum techniques.

Karthala volcano on the oceanic island of Grande Comore, West-Indian Ocean, is one of worlds' largest active alkaline basalt shield volcanoes, with 5 eruptions since 1991. In the last century the volcanic activity mainly concentrated within the 3.5 x 2.8 km large area of the summit caldera complex. Limited study has so far been carried out to unravel the structure and geometry of the summit caldera complex, the collapse chronology and the recent changes caused by the 2005 - 2007 eruption phases. Two exploratory missions to the Karthala summit in July 2011 led to an updated overview of the volcano-tectonic structures, evidence of the local orientation of the principle stresses and a preliminary stratigraphy of the 400 m deep rock sequence exposed in the caldera walls. Three overlapping caldera's build the main structure of the complex, with vertically-subsided blocks forming intermediate terraces along the caldera structures. Within these blocks, several graben-like structures with N-S and N135E orientations are evidencing a secondary influence of extension during or after the overall vertical collapse. One of the southwestern caldera blocks shows a 'tilted block' morphology, with a caldera-inward rotation. 'Choungou Changouméni', a nested pit crater in the Northern caldera, was 30 m deep in 1965 and has now been almost completely filled with pyroclastic deposits and lava flows. Caldera walls in the whole complex consist of massif meter-thick alkali-basalt flows with decimetric intercalations of weathered pyroclastic layers, and are topped by scoria and tuff cones. The caldera floor itself is covered by volcanic ash, lapilli, and massif scoriaceous surfaces of ancient flows. At the intersection of the 3 main caldera structures two deep explosion craters are located, together named 'Choungou Chahalé'. These were the centres of recent phreatic activity. Their vertical walls show a sequence of thick alkali basalt flows and hold numerous cross-cutting dykes which fed small-scale eruptive cones, vertical degassing fissures and former caldera levels. Fissures with active fumaroles inside the two explosive craters and in the area between Choungou Chahalé and Changouméni are indicating a focus area in the hydrothermal activity. It is this hydrothermal system that is suggested to have controlled the phreatic nature of recent eruptions (1991, 2005 and 2007). Several pyroclastic beds and cones affected by block and bomb impacts inside the caldera complex and around the summit area testify the high explosive nature of these recent eruptions, in contrast with the effusive Hawaiian-style character generally associated with Karthala. The orientation of caldera-bounding structures, eruption and fumarolic fissures, dykes as well as the orientation of intra-caldera extensional faults indicate one minor (E-W) and two major volcano-tectonic directions (N-S and N135S). The latter are concurring with previously identified regional stress orientations and rift zone's orientations on Karthala flanks. Upcoming field work will be dedicated to the exhaustive structural and stratigraphic mapping of Karthala caldera as it provides exceptional exposure to document the internal architecture of an alkali basalt shield volcano and a complex caldera subsidence chronology.

Donuea collustrata Bosselaers & Dierick sp. nov. Figs. 1 A���E; 2 A���F; 3 A���M; 4 A���I. Type material. Holotype male: Madagascar, Foulpointe, forest on clay soil, beating vegetation, July 1995, A. Pauly leg. (MRAC 206172). Paratype male, in copal from the Sambava area, NE Madagascar, MRAC. Diagnosis. The species can be distinguished from the type species Donuea decorsei Simon, 1903, by its bifid RTA as opposed to a simple one (Simon 1903: 138), its large, bifurcated MA, a simple, pointed conductor situated ventrally instead of dorsally of MA and its shorter embolus which does not describe a circular loop before passing behind the tegulum (Figs. 1 F, 4 C, F, I). Description. Body length without chelicerae (holotype): 4.34, with chelicerae: 5.76. Carapace length: 1.81; w: 1.55, oval, yellow brown, darker in eye region, and with two brown lateral bands (Fig. 1 A���B, D). Fovea short and deep, pale brown, length 0.08, anterior end 1.14 from front. Eight eyes in two rows, ringed with black, AER w: 0.82, recurved from above, slightly procurved from front, PER w: 0.89, procurved from above, strongly procurved from front (Figs. 1 A, D, 3 M). MOQ depth: 0.32, anterior w: 0.37, posterior w: 0.42. All eyes subequal, ALE oval, others circular. All four median eyes with dark retina restricted to median 2 / 3. Anterior median eyes slightly closer to each other than to ALE. Eyes of PER equidistant, separated by about twice their diameter. ALE and PLE touching, on common tubercle. Clypeus vertical, 1 / 3 of diameter of AME. Chilum orange-brown, sclerotised, split (Fig. 3 M). Chelicerae large, yellow brown, elongated and pointing forward, parallel to the longitudinal axis of the body (Figs. 1 A���D, 2 C, F, 3 A). One large kneeshaped seta and a row of long, curved setae on ACR, cheliceral fangs brown. Six teeth on ACR, largest one closest to fang base, followed by an isolated very small tooth and two pairs of small teeth separated by a small distance. Seven teeth on PCR, a pair of medium sized teeth close to fang base, followed at some distance by five small teeth in a row. Sternum length: 1.05; w: 0.95, smooth, yellow, elongated and shield-shaped, with pale broad and blunt ICS between legs I���II and II-III, and thin, brown and pointed PCT facing all coxae (Fig. 1 C, E). Pleural bars (Bosselaers & Jocqu�� 2002: 247, fig. 1 P; Simon 1892: 11, fig. 29) yellow-brown continuous strips, weakly protruding between coxae. Labium brown, subtrapezoidal, as long as it is wide at its base, with white, thickened anterior rim. Endites subrectangular, with apical hair tuft and serrula, no oblique depression (Fig. 1 C, E). Abdomen cream, unicolorous ventrally and with two lateral, purple brown bands dorsally (Fig. 1 A���B, D). ALS contiguous, conical, with short, blunt apical segment. PMS very thin and slender, PLS subcylindrical, mottled with grey, with pale, rounded apical segment (Figs. 1 B���D, 3 A). Legs yellow, fe, ti and mt ringed with grey basally and/or terminally (Figs. 1 A���C, 2 B���C, F). No trochanter notch, no retrocoxal hymen (Raven 1998; Bosselaers & Jocqu�� 2002), patellar indentation long and narrow, �� of pa length. Metatarsi III and IV with sparse ve terminal preening brush. Tarsi with two claws and dense claw tufts. Leg formula 1423. Leg spination (Fig. 2 E): fe: palp do 0-1 - 1 rlv 1 - 1 - 1 - 1 - 1 -0; I pl 0-1 - 1 - 1 do 0-1 - 1 - 1; II pl 0- 0- 0-1 do 0-1 - 1 - 1; III do 0-1 - 1-2; IV do 1 - 1 - 1 - 1-2 - 2; pa: palp pl 1; ti: palp pl 2 -0-0; I pl 0-1 - 1 ve 2 - 2 - 2 - 2 - 2; II ve 2 - 2 - 2 - 2; III rl 0-1 -0 plv 1 - 1 -0; IV rl 0-1 - 1 -0 plv 1 - 1 -0 rlv 0- 0-1; mt: I pl 1 -0-0 ve 2 - 2 - 2; II ve 2 - 2 -0; III pl 0- 1 -0 rl 1 -0-0 ve 2 -0-0; IV rl 0- 0-1 ve 2 - 0-2. Male palp with a simple, blunt PTA (Figs. 3 D, E, L, 4 F, I) and a bifid RTA consisting of a long, pointed do part and a cup-shaped ve part (Figs. 3 I, J, K, L, 4 A���C). Palpal tarsus elongated and piriform, with a large, bifid, flag-shaped MA (Figs. 3 C���F, 4 D���I), a simple, blunt-tipped conductor situated ventrally of the pl branch of the MA (Figs. 3 C���F, L, 4 D���I) and a long embolus emerging from below the rl branch of the MA, proceeding basally and subsequently passing behind the tegulum (Figs. 3 B���C, G���K, 4 A���C, F). Female. Unknown. Etymology. The species epithet collustrata, irradiated, refers to the X-ray tomography technique used as an aid in the description of the present species. Remarks. The specimen preserved in copal clearly is conspecific with the field-captured holotype. It has the same size (body length 4.21) and general morphology, and both specimens are identical with respect to a number of diagnostic details. Leg spination of the copal specimen is identical to the holotype although a few spines are missing, probably having been lost when the animal got caught in the sticky resin (Figs. 2 E���F). The copal specimen has lost most of its original colour, the abdomen being partly transparent and showing two dark spots in the anterior half, presumably corresponding with the book lungs. However, the leg annulations have been mostly preserved and coincide with those of the field-captured animal (Figs. 1 A���C, 2 B, C, F). Most significantly, palpal structure of both specimens is identical in minute detail, as can be proven by juxtaposing stereomicroscope observations of the field-captured holotype with X-ray micro-CT scans of the copal preserved specimen (Fig. 4 A���I). The assignment of Donuea to Liocranidae is debatable, and it can indeed be argued that the genus would be better placed in Clubionidae. However, a formal transfer is outside the scope of the present contribution., Published as part of Bosselaers, Jan, Dierick, Manuel, Cnudde, Veerle, Masschaele, Bert, Hoorebeke, Luc Van & Jacobs, Patric, 2010, High-resolution X-ray computed tomography of an extant new Donuea (Araneae: Liocranidae) species in Madagascan copal, pp. 25-35 in Zootaxa 2427 on pages 27-32, DOI: 10.5281/zenodo.293907, {"references":["Simon, E. (1903) Descriptions d'arachnides nouveaux de Madagascar, faisant partie des collections du Museum. Bulletin du Museum d'histoire naturelle de Paris 9, 133 - 140.","Bosselaers, J. & Jocque, R. (2002) Studies in Corinnidae: cladistic analysis of 38 corinnid and liocranid genera, and transfer of Phrurolithinae. Zoologica Scripta, 31, 241 - 270.","Simon, E. (1892) Histoire Naturelle des Araignees. Tome 1. Roret, Paris. 1084 pp.","Raven, R. (1998) Revision of the Australian genera of the Miturgidae with a preview of their relationships. In: XIVth International Congress of Arachnology, Abstracts, p. 31."]}

Gypsum crystallization on natural building stones due to sulphatation processes is a well known and widely described phenomenon in deterioration studies. The gaseous SO2 of the polluted environment reacts with the carbonate of the stone, resulting into gypsum (CaSO4.2H2O) crystallization on the surface and inside the porous structure of the material. In order to obtain quantitative information on porosity and pore structure change before, during and after sulphatation, the process should be monitored on the same sample. With the aid of non-destructive high-resolution X-ray computed tomography we investigated various types of porous limestones before, during and after in vitro-induced gypsum crystallization processes. A 3D image with a resolution of 2.5 µm was obtained during each step of gypsum crust formation. Besides the visualization of the gypsum crystallization, also quantitative information on porosity and pore structure changes could be obtained. For each stone type, radial porosity, open pore structure, partial porosity and distribution of equivalent and maximum opening of the pores has been calculated with the software program Morpho+. The blistering of the gypsum crust on the calcareous sandstone has been quantified, and the secondary porosity provoked by the dissolution of calcite has been calculated in 4 dimensions. The results of this research contribute to a better understanding of the evolution of pore structure changes due to deterioration. This process results in zones of changed porosity with a subsurface weakening due to loss of coherence and crustal induration. A better understanding thus allows quantification of future material loss and durability change.

Sandstones are used in many contemporary and historical buildings. With time, these buildings become dark and a surface crust is formed. Generally, these crusts mainly consist of minerals of which the constituents were mobilised from the interior of the stone, and material from the surrounding environment like air pollutants and dust. Many traditional techniques, such as optical microscopy, Scanning Electron Microscopy and the Drilling Resistance Measurement System, have been used to study these crusts in the past. The advent of more advanced techniques allows a better characterisation of sandstone surface crusts, commonly present in urban stone decay. High-resolution X-ray radiography and tomography, micro X-ray absorption spectroscopy (µ-XANES) and 2D micro-XRF scanning at laboratory and synchrotron sources, combined with more traditional research methods were applied to the study of a sandstone surface crust. This shows that the combination of these highly advanced techniques, which were not designed with the purpose of answering geological or environmental questions, can generate complementary 2D and 3D imagery of geological materials, opening up new approaches in the study of element migration inside porous geomaterials. Capsule: I hereby state that this work is significant to the rest of the scientific community.

Foraminifera (Forams) are single-celled amoeba-like organisms in the sea, which build a tiny calcareous multi-chambered shell for protection. Their enormous abundance, great variation of shape through time and their presence in all marine deposits made these tiny microfossils the oil companies’ best friend by facilitating the detection of new oil wells. Besides the success of forams in the oil and gas industry, they are also a most powerful tool for reconstructing climate change in the past. The shell of a foraminifer is a tiny gold mine of information both geometrical as chemical. However, until recently the best information on this architecture was only obtained through imaging the outside of a shell with Scanning Electron Microscopy (SEM), giving no clues towards internal structures other than single snapshots through breaking a specimen apart. With X-ray computed tomography (CT) it is possible to overcome this problem and uncover a huge amount of geometrical information without destructing the samples. Using the last generation of micro-CT’s, called nano-CT, because of the sub-micron resolution, it is now possible to perform adequate imaging even on these tiny samples without needing huge facilities. In this research, a comparison is made between different X-ray sources and X-ray detectors and the resulting image resolution. Both sharpness, noise and contrast are very important parameters that will have important effects on the accuracy of the results and on the speed of data-processing. Combining this tomography technique with specific image processing software, called segmentation, it is possible to obtain a 3D virtual representation of the entire forams shell. This 3D virtual object can then be used for many purposes, from which automatic measurement of the chambers size is one of the most important ones. The segmentation process is a combination of several algorithms that are often used in CT evaluation, in this work an evaluation of those algorithms is presented. Difficulties arising when the forams shell is filled with material but it still remains possible to perform adequate segmentation. The void inside the shell corresponds to the chambers of the foram and the inter-chamber connections. Using automatic separation algorithms it is possible to obtain the shape of individual chambers. The results from the segmentation process can then be used to perform a multitude of analysis on each foram. Out of the shells geometry one can derive variations in shell thickness, shell density and shell porosity. Since the geometry of each individual chamber can be derived, it is possible to track chamber size variation for one foram or between two different forams, the difference in orientation and distance between the chambers. In this work the algorithms and procedures have been applied on two forams: A. Pseudouvigerina sp., a benthic foram that lived within the sediments at the seafloor. It dates from the earliest Paleocene, 65 Ma and was collected near Brazos River, Texas. B. Globigerinoides, a modern planktic foram, living in the upper part of the water comlumn in the open ocean. The test settled on the seafloor after death and was recently collected from the seafloor at 2900 m water depth at Nazca Ridge in the eastern Pacific Ocean. It was found that foram A consists of 15 chambers with a total volume of 1.8 x 106 µm³ and shows progressive growth of consecutive chambers (average of 1,5 magnification). After the large globular initial chamber, which indicates asexual reproduction, each chamber is slightly larger than the previous one. In the later stages the chambers develop lateral edges with a thickened margin, leading to a distinct triangular shape in cross section. Foram B on the other hand has a distinct trochospiral coil (like a snail), consisting of 16 chambers with a total volume of 91 x 106 µm³. The entire shell thickens with every successive chamber, so that the initial part of the test is embraced in a thick calcite crust. The chambers grow rapidly in size (average magnification of 2,24 ), which is typical for most planktic foraminifera. The globular shape aids in the buoyancy of the specimen for its planktic way of life.

In this study, two different applications of the combination of XRF and µCT will be discussed. The first application is a way of obtaining chemical information on the different compounds in the inner part of a granite. This information can not be measured directly with XRF, but can be derived from the XRF spectra and µCT data together. In the second application, the chemical elements present in volcanic rock are analysed, providing information about their origin.

During the last decades, X-ray micro CT has become a well established technique for non-destructive testing in a wide variety of research fields. Using a series of X-ray transmission images of the sample at different projection angles, a stack of 2D cross-sections is reconstructed, resulting in a 3D volume representing the X-ray attenuation coefficients of the sample. Since the attenuation coefficient of a material depends on its density and atomic number, this volume provides valuable information about the internal structure and composition of the sample. Although much qualitative information can be derived directly from this 3D volume, researchers usually require more quantitative results to be able to provide a full characterization of the sample under investigation. This type of information needs to be retrieved using specialized image processing software. For most samples, it is imperative that this processing is performed on the 3D volume as a whole, since a sequence of 2D cross sections usually forms an inadequate approximation of the actual structure. The complete processing of a volume consists of three sequential steps. First, the volume is segmented into a set of objects. What these objects represent depends on what property of the sample needs to be analysed. The objects can be for instance concavities, dense inclusions or the matrix of the sample. When dealing with noisy data, it might be necessary to filter the data before applying the segmentation. The second step is the separation of connected objects into a set of smaller objects. This is necessary when objects appear to be connected because of the limited resolution and contrast of the scan. Separation can also be useful when the sample contains a network structure and one wants to study the individual cells of the network. The third and last step consists of the actual analysis of the various objects to derive the different parameters of interest. While some parameters require extensive calculations, others can be obtained easily. The different parameters which can be obtained are related to the size, shape and orientation of the objects. Additionally, the connectivity of a network can be analysed by comparing the set of objects before and after separation. The size of each object can be characterized by its volume, equivalent diameter and the diameter of the maximum inscribed sphere. The surface can be determined by extracting a polygonal mesh from the volume data. Calculation of Feret’s diameter reveals information about the objects elongation. Additionally, the moments of inertia can be calculated to obtain the axes of an equivalent ellipsoid. This data can be used to determine the main axis and therefore the orientation of the object within the sample. Feret’s diameter and the equivalent ellipsoid are representative for the basic shape of the object. Additionally, using a routine that fills concave regions, the convex hull of an object can be retrieved to quantify the convexity. Different ratios can be defined, which compare the surface area with the volume of the object (sphericity) or the volume of the convex hull. These ratios and the convexity characterize the objects roughness and shape. The described parameters are used to characterize volcanic deposits found in the area west of Lac Pavin (lake in Auvergne, France). The samples are taken from the most recent ‘red scoria’ layer, which is believed to be the result of the latest eruption in Western-Europe. There is however, ambiguity on the origin of the layer in terms of age and placement. The aim is to fingerprint this layer in such a way that the various eruptions in the area can be distinguished from one another. Measurements of the vesicle density, volume and connectivity of the investigated deposits provide information about the intensity of the eruption. Additionally, vesicle geometry can be related to the magmatic permeability, which is essential to the dynamics of the eruption.

Cenotextricella simoni Penney sp. nov. Figs 1���12 Type material. Holotype male: in lowermost Eocene amber from the Paris Basin (MNHN PA 327). Etymology. The specific epithet is a patronym in honour of the famous French arachnologist Eugene Simon. Diagnosis. As for the genus. Description. Male holotype. Body length 1.08 mm. Carapace elevated in the cephalic region, bearing eight eyes; anterior medians smallest and contiguous, remainder subequal; lateral eyes contiguous and not on a raised mound, posterior medians slightly separated (Figs 1, 3, 6). Sternum as wide as long, evenly rounded posteriorly, coxae 4 clearly separated (Fig. 2). Labium three times wider than long, unnotched; endites directed across labium but do not meet in the midline. Chelicerae vertical, not fused along their length and with promarginal dentition (Figs 2, 3, 6). Abdomen ovoid, with a large dorsal scutum (with sparse but distinct setae, not detected by the VHR-CT) and a ventral scutum in the epigastric region surrounding the pedicel (Figs 1, 2, 4���6). Relative order of leg length 1,2, 4,3, with distinctly shortened metatarsi (0.5 �� tarsi length) on all legs (Figs 1���5). Legs with erect, bristle-like setae (not picked up by the VHR-CT) as follows: one distal on each patella, one proximal on each tibia, one distal on tibiae 1, 2 and 4 (Figs 11, 12). Spinnerets situated posteriorly in a compact group, with a distinct colulus (Figs 2, 4, 5). Pedipalp (Figs 6���10) with embolus wrapped around a conductor (Figs 6, 9); tibia complex, flattened and abutting on the cymbium, with broad prolateral extension (Fig. 8) and a distinct tibial hook visible in retrolateral view (Fig. 9); patella with a proximal, retrolateral knob-like projection (Figs. 6, 9). Distribution: Early Tertiary (lowermost Eocene) Paris Basin amber forest., Published as part of Penney, David, Dierick, Manuel, Cnudde, Veerle, Masschaele, Bert, Vlassenbroeck, Jelle, Hoorebeke, Luc Van & Jacobs, Patric, 2007, First fossil Micropholcommatidae (Araneae), imaged in Eocene Paris amber using X-Ray Computed Tomography, pp. 47-53 in Zootaxa 1623 on page 49, DOI: 10.5281/zenodo.179249

Cenotextricella Penney gen. nov. Type species. Cenotextricella simoni sp. nov. Etymology. ��� Ceno ��� from Cenozoic, the geological era from which the type species originates, plus ��� textricella ��� from Textricella, a closely allied extant genus. Diagnosis. Male Cenotextricella can be distinguished from other (extant) Micropholcommatidae by the presence of a proximal, retrolateral knob-like pedipalpal patellar apophysis (Fig. 9), by the short, curved embolus wrapped around a conductor in retrolateral view (Figs 7, 9), and by the shape of the highly modified tibia (Figs 7���10). Some extant Australian and New Zealand Textricella possess a similar patellar apophysis, and sometimes also a modified tibia (e.g. T. complexa Forster), but these palpal segments are otherwise nothing like those observed in the type specimen. Females of Cenotextricella are unknown. Description. See the description (below) for the type species. Distribution: Early Tertiary (lowermost Eocene) Paris Basin amber forest., Published as part of Penney, David, Dierick, Manuel, Cnudde, Veerle, Masschaele, Bert, Vlassenbroeck, Jelle, Hoorebeke, Luc Van & Jacobs, Patric, 2007, First fossil Micropholcommatidae (Araneae), imaged in Eocene Paris amber using X-Ray Computed Tomography, pp. 47-53 in Zootaxa 1623 on page 49, DOI: 10.5281/zenodo.179249