Mactrotoma Dall 1894

Genus Mactrotoma Dall, 1894 Type species. Mactra fragilis Gmelin, 1791, [Dall, 1894 b, original designation]. Diagnosis. Shell trigonal to subcircular, posterior area covered by a thick periostracum and defined by a line. Distribution. Atlantic coast of America, from United States to Brazil, Pacific coast of North America to Peru, South east Asia.