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Three new species from the Aleutian Islands are described. Echinoclathria seguama n. sp. has only four congeners in the region, it is closest to E. vasa and differs from it in the dimensions of all spicule categories. Stelodoryx jamesorri n. sp. is unusual as it has a plumoreticulate choanosomal skeleton instead of the usual reticulate arrangement in other Stelodoryx. To accommodate the species in Stelodoryx we amend the genus definition accordingly. Choanosomal styles, common in Stelodoryx, tend to merge into strongyloxeas in S. jamesorri. Additionally, spicule dimensions deviate from other congeners of the region. The tendency of replacing choanosomal styles by strongyloxeas goes even further in Stelodoryx strongyloxeata n. sp. which has very conspicuous, thick, fusiform strongyloxeas, that differ, apart from being strongyloxeas, also considerably in size from the styles of other species. S. strongyloxeata n. sp. also has style-like tornotes, a characteristic that it shares with S. siphofuscus, but dimensions of style-shaped tornotes are different.

A sponge collected along the Aleutian Islands of Alaska revealed an unusual combination of characters including ectosomal acantho - tornotes never before observed. Assignment to Poecilosclerida is without any doubt due to the presence of chelae but assignment to family is more problematic because 1) there is no family of Poecilosclerida (or any other demosponge) with ectosomal acantho-tornotes, and 2) the combination of occurring spicules and their arrangement does not conform completely to any Poecilosclerid family. Thus family assignment is only possible by amending the concept of an existing poecilosclerid family and allow for spined as well as smooth tornotes and a confusedly plumose choanosomal arrangement of megascleres. We suggest assignment to Hymedesmiidae as this requires relatively slight changes compared to other Poecilosclerid families. We suggest the erection of Acantorna n. gen. to accommodate Acantorna tahoma n. sp. The new genus and species differ from all other Hymedesmiid genera in the possession of the characters necessary for the suggested amendment. Additional differences to each Hymedesmiid genus are added.

Ten new species of demosponges, assigned to the orders Poecilosclerida, Axinellida and Dictyoceratida, discovered in the Gulf of Alaska and along the Aleutian Island Archipelago are described and compared to relevant congeners. Poecilosclerida include Cornulum globosum n. sp., Megaciella lobata n. sp., M. triangulata n. sp., Artemisina clavata n. sp., A. flabellata n. sp., Coelosphaera (Histodermion) kigushimkada n. sp., Stelodoryx mucosa n. sp. and S. siphofuscus n. sp. Axinellida is represented by Raspailia (Hymeraphiopsis) fruticosa n. sp. and Dictyoceratida is represented by Dysidea kenkriegeri n. sp. The genus Cornulum is modified to allow for smooth tylotes. We report several noteworthy biogeographical observations. We describe only the third species within the subgenus Histodermion and the first from the Indo-Pacific Region. Additionally, the subgenus Hymerhaphiopsis was previously represented by only a single species from Antarctica. We also report the first record of a dictyoceratid species from Alaska. The new collections further highlight the richness of the sponge fauna from the region, particularly for the Poecilosclerida.

Two new species of the genus Stelletta and one new species of Ancorina are described from the Aleutian Islands of Alaska and compared to congeners of the region. This is the first record of the genus Ancorina in the North Pacific Ocean. Stelletta ovalae Tanita 1965 is also reported for the first time from the Bering Sea and Alaska.

Four new species of Haplosclerida are described from the Aleutian Islands, Alaska: Callyspongia mucosa n.sp., Cladocroce infundibulum n. sp., Cladocroce attu n. sp. and Cladocroce kiska n. sp. The new species are described and compared to congeners of the region. This is the northernmost record of the genus Callyspongia and the first record of the subgenus Callyspongia from the North Pacific Ocean. To accommodate Cladocroce kiska in its genus the definition has to be broadened to allow sigmas.