ACTINOPODOUS HOLOTHUEIOIDEA. 209 



a more or less round central hole, from the edge of which pro- 

 jects a crown constructed of four or more slightly curved arms. 

 The central hole is covered in every case with an opercular plate 

 through which there may open from one to several openings. 

 Small wheel-like plates are 0.052 mm. in diameter, with about 15 

 holes (four in the center and eleven around the periphery). Large 

 wheels are most numerous in the dorsal perisome and the pro- 

 cesses ; they are very few and scattered in the ventral perisome 

 and pedicels. Besides, the dorsal perisome contains some wheel- 

 like plates ; while in the ventral perisome there are numerous 

 small wheel-Hke plates and isolated large wheels (Slotee). Sup- 

 porting rods and end-plates present in pedicels. CValcareous ring 

 rudimentary, fragile and spongy. PoKan vesicle, one. Stone-canal 

 opens to the exterior by several pores. Genital bundles, two. 

 Size, 20 cm. long and 4 cm. broad. Color, greyish white ; back, 

 dark violet in alcohol, violet when fresh (Ludwig). 



Remarks .-—The specimens are considerably smaller than the 

 " Challenger " specimens, being respectively 53 mm. x 13 mm., 

 33 mm. x 10 mm. and 00 mm. x 19 mm. They are at present much 

 shrunk, and there can be no doubt that they were much longer 

 when living : in fact Aoki makes a statement to that effect. 



Tentacles 20, large, non-retractile, in some specimens decided- 

 ly yellowish. Dorsum vaulted, ventrum flat. Along each side of 

 the body there is a series of large pedicels ; in the first speci- 

 men, 17 on the left side and 19 on the right; in the second, 17 

 01 18 on each side; in the third, 19 on the left, 20 on the right, 

 being crowded and smaller toward the posterior end. Along the 

 median ventral ambulacrum, the second specimen has about 11 

 pedicels somewhat smaller than the lateral, and arranged in a 

 zigzag row. Of these, about nine are in the posterior half of the 



