no. 2073. HOLOTHURIANS FROM NORTHWEST PACIFIC— OHSHIMA. 281 



86. (?) PSOLUS JAPONICUS Ostergren. 



Psolus japonicus Ostergren, Zur Anatomie der Dendrochiroten, 1898, pp. 135- 

 136. — Britten, Holothurien a. d. japan, u. ochotsk. Meere, 1907, pp. 146- 

 147.— Ohshima, Zool. Mag. (Japanese), vol. 25, No. 293, pp. 130-132, pi. 5, 

 figs. 1-9. 



Station 4807. Two specimens. 

 Station 4808. Two specimens. 



The largest specimen measures 40 mm. long, 32 mm. wide, and 10 

 mm. thick. Deposits of sole in a single layer, only 100-280/* in diam- 

 eter; differing from those of Ps. squamatus in that the solid inter- 

 spaces are broader than apertures and that knobs extend to form a 

 second layer. There are 10-11 scales between the mouth and the 

 anus, 20-30 in a transverse line at the broadest part of the body. 



My identification may be criticized. The specimens differ from 

 those described by Ostergren and Britten, first, in that the dorsal 

 scales are thin and numerous; second, in the absence of large plates 

 0.4 mm. wide; and third, in the occasional presence of some scattered 

 pedicels in the odd ambulacrum. They can not be referred to any 

 other known species. 



Habitat. — Tsugaru Strait (Ostergren, 1898); west coast of southern 

 Sakhalin (Britten, 1907). 



Genus PSOLIDIUM Ludwig. 



87. PSOLIDIUM VITREUM, new species. 



Plate 11, fig. 32. 



Station 4979. One specimen. 



Station 5084. Three specimens. 



Station 5087. Five specimens. 

 Body as seen from dorsum elliptic, with a strongly vaulted dorsum 

 and a concave ventrum very sharply distinguishable from the other 

 parts. Mouth anterodorsal, anus decidedly dorsal, both borne on a 

 low, conical prominence. Young individuals are quite flat. As meas- 

 ured in the largest specimen, sole is 21 mm. long and 14 mm. wide; 

 distance from mouth to anus, 20 mm.; height of body about 9 mm. 

 Color white and glassy all over, ventral sole very thin and semi- 

 transparent. Tentacles 10, midventral pair being smaller than the 

 rest. Pedicels nonretractile, arranged in a zigzag row in each ven- 

 trolateral ambulacrum, just on the edge of the sole. The odd am- 

 bulacrum has only a very few, sparsely scattered pedicels, Minute 

 papilla-like pedicels are sparsely scattered all over the dorsum. 

 They are 350/1 long and 100/* across. Deposits of sole are round 

 or oval plates often overlapping one another (pi. 11, fig. 32); 

 holes large, quite regularly arranged, 6.5-53/z across, average 25/<, 

 smaller or often obliterated in old individuals. At each node of the 



