230 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.48. 



16. PSEUDOSTICHOPUS NUDUS, new species. 



Station 4768. Seven specimens. 



Station 4769. One specimen. 



Station 4771. Four specimens. 



Station 4772. One specimen. 



Station 4774. Five specimens. 



Station 4775. Five specimens. 



Station 4781. One specimen. 



Station 4966. Five specimens. 



Body subcylindrical, almost uniform breadth throughout, both 

 extremities rounded. Length 190 mm., breadth 50 mm., and height 

 30 mm. Mouth ventral, anus in a conspicuous pygal furrow. Sur- 

 face of body almost naked, sometimes coated with very few sponge 

 needles. Color whitish, often light yellow or brownish. Tentacles 

 20. Numerous pedicels form a broad zone along the mid ventral 

 ambulacrum, there being about 8 pedicels in a transverse line. 

 Toward the posterior part of body there is a groove along the median 

 line. The pedicels are very peculiar in shape, each consisting of a 

 number of oval, knoblike parts, 0.3-0.5 mm., united into a group 

 measuring 1-2 mm. in diameter. Along lateral margin of ventrum 

 are very low processes, often invisible, probably in alternate rows. 

 Dorsal papillae, 1-1.5 mm. long, forming a double row along each 

 ambulacrum, very sparse, separated by intervals of about 10 mm. 

 Supporting rods of tentacles are curved, slightly spinous, often with 

 irregular branches. Near tip of papillae are found slender rods 

 usually with a knoblike thickening at the middle, but often irregu- 

 larly branched. No deposits whatever are found elsewhere. Calca- 

 reous ring is of the usual form, each segment often with a pair of 

 minute teeth on the posterior margin. Polian vesicle single, respi- 

 ratory trees two. Genital tubes undivided,' arranged in a row along 

 each side of dorsal mesentery. 



Some strongly contracted specimens show along each side of body a 

 low thickened ridge, "bourrelet epais," as in Ps. depressus Herouard. 

 Ps. pustulosus Sluiter differs from the present species in shape and 

 arrangement of ambulacral appendages. 



Habitat. — Aleutian Islands; off Kii, Honshu. 



Type.— Cat. No. 34150, U.S.N.M. 



17. PSEUDOSTICHOPUS UNGUICULATUS, new species. 



Plate 8, figs. 7a-c. 



Station 4960. One specimen. 

 Station 5083. Two specimens. 

 Station 5084. One specimen. 

 Body 90 mm. long, 35 mm. broad, ventrum flat, dorsum strongly 

 vaulted. Mouth directed ventrad, anus situated in a deep pygal 



