no. 2073. HOLOTHURIANS FROM NORTHWEST PACIFIC— 0H8HIMA. 229 



present in interambulacra thinly scattered, those belonging to the 

 midventral ambulacrum being almost indistinguishable from them. 

 Larger pedicels, up to 2 mm. long, form a double row on each ventro- 

 lateral ambulacrum. In the dorsal ambulacra smaller papillae (?) 

 are arranged in double rows. No deposits are present in general 

 perisome or genital tubes. In larger pedicels an end-plate 140/* in 

 diameter is present, and near it a few supporting rods (pi. 8, figs. 

 6a, b)., 50-120/* long, and always with a slight knob at the middle. 

 Similar rods are found in tentacles, but these are much larger and are 

 armed with short processes near the extremities. In the perianal 

 region are found scattered irregular spiny bodies of varying com- 

 plexity (fig. 6c), 60-200//. in length. The simplest ones are X-shaped. 

 Calcareous ring well developed, radial segments having a pair of 

 accessory processes near the outer edge of the anterior end. Polian 

 vesicle single, genital tubes undivided, in two tufts. Respiratory 

 trees two, well developed. 



The present species agrees in many respects with Ps. pustulosus 

 Sluiter, but differs from it above all in lacking the series of large stout 

 warts along each side of ventrum. 



Habitat. — Off Shiribeshi, Hokkaido. 



Type.— Cut. No. 34148, U.S.N.M. 



15. PSEUDOSTICHOPUS ARENOSUS, new species. 



Station 4915. One specimen. 



Body more or less fusiform, 45 mm. long, 15 mm. broad. Mouth 

 terminal but directing ventrad, anus situated in a vertical pygal fur- 

 row. Surface of body covered with numerous Globigerina shells 

 and a few sponge needles, gray in color all over. Tentacles 20. 

 There are conspicuous double rows of ambulacral appendages along 

 paired ambulacra, of which the ventral ones have more crowded and 

 larger pedicels, which may be as long as 1 mm. Along the odd am- 

 bulacrum no distinct row of pedicels can be found. Irregular spinous 

 bodies similar to those in Ps. molpadioides and 50-175/* long are 

 found scattered in perianal region. Pedicels have end-plates only, 

 which measure up to 90/* in diameter. Supporting rods of tentacles 

 bear numerous knobs. No deposits are found elsewhere. Calca- 

 reous ring well developed, radials being very thick. Polian vesicle 

 single, genital tubes undivided. Respiratory trees two. 



The present species very much resembles Ps. molpadioides, only 

 differing in the absence of supporting rods in pedicels and in details 

 of rods in tentacles. 



Habitat. — Off Koshiki Islands, west of Kyushu. 



Type.— Cat. No. 34149, U.S.N.M. 



