1923] Clark, Echinoderms from Loiver California 161 



HOLOTHURIOIDEA 

 Molpadia musculus Risso 

 Molpadia musculus Risso, 1826, 'Hist. Nat. Princip. Product. Europe Mer.,' p. 

 293. 



There is a single Molpadia from Station 5684, in fine condition, 80 

 mm. long by 25 mm. in diameter where largest, and with the caudal 

 portion 13 mm. long. The color is pale gray and there are no phosphatic 

 bodies. The calcareous particles seem to warrant referring it to this 

 species, but it is certainly not a typical example. 



Cucumaria abyssorum Theel 



Cucumaria abyssorum Theel, 1886, 'Rep. Voy. 'Challenger,' Zool.,' XXXIX, 

 p. 66. 



There are two additional specimens from Station 5684 and five 

 from 5691. They are well preserved and several show their ten tentacles. 

 They are 50 to 95 mm. long and in the largest the genital papilla is 

 conspicuous. 



Psolus squamatus (0. F. Muller) 



Holothuria squamata O. F. Muller, 1776, Proc. Zool. Dan., p. 232. 

 Psolus squamatus McAndrew and Barrett, 1857, Ann. Mag. Nat. Hist., (2) 

 XX, p. 45. 



There is another large Psolus at hand from Station 5695, measuring 

 80 mm. long by 55 mm. wide and 30 mm. high. It seems to me almost 

 incredible that these specimens can really have been taken at a depth of 

 534 fms. and not show any differences to distinguish them from speci- 

 mens taken in shallow water on the Norwegian coast. The species of 

 Psolus are in need of critical revision and the Pacific coast material is 

 not at present sufficient to make such a revision satisfactory. 



Thyonepsolus nutriens H. L. Clark 

 Thyonepsolus nutriens H. L. Clark, 1901, Zool. Anz., XXIV, p. 168. 

 There is a small psolid at hand with only the unsatisfactory label 

 "Gulf of California" to indicate whence it came. It is 12 mm. long by 

 6.5 mm. wide and about 4 mm. high. The calcareous deposits in the sole 

 can be roughly grouped in three classes and are almost exactly like those 

 of Psolidium dorsipes Ludwig. But the dorsal surface is quite unlike 

 Psolidium and is exactly as described for Thyonepsolus, soft, thick, with 

 no visible scales or plates, and very numerous pedicels not arranged in 

 longitudinal series. The validity of Thyonepsolus has been questioned 

 and some have relegated the genus to the synonymy of Psolidium, but 



