PSOLIDIUM-BIDISCUM, A NEW SHALLOW-WATER PSOLID SEA-CUCUMBER (ECHINODERMATA, HOLOTHUROIDEA) FROM THE NORTHEASTERN PACIFIC, PREVIOUSLY MISIDENTIFIED AS PSOLIDIUM-BULLATUM OHSHIMA

A common west-coast psolid sea cucumber, formerly identified as Psolid ium bullatum Ohshima, 1915, is described as a new species. Psolidium b idiscum n.sp. has two types of ventral ossicles, one type of dorsal cu p, and 10 scales between the mouth and anus. Psolidium bullatum Ohshim a, 1915 has one type of ventral ossicle, no dorsal cups, and 19 scales between the mouth and anus. Psolidium bidiscum is known from southeas tern Alaska south to Monterey, California, between 0 and 200 m in dept h. Psolidium bidiscum is compared with six other species of Psolidium from the eastern Pacific.