148 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 8 



Psoitis squamatus H. L. Clark, 1901, p. 165; 1901, p. 491.— Ohshima, 



1915, p. 280. 

 P solus pauper, Liidwig, 1894, p. 139. 



Diagnosis. — Large form (sole up to 13 cm. long) ; scales thin, 

 smoothly overlapping, about 12 between oral and anal scales. Oral and 

 anal apertures surrounded by a number of triangular scales but not de- 

 veloped as regular valves, except in very young individuals. Sole thin, 

 with marginal feet. Spicules in sole 4-holed delicate buttons (0.07-0.09 

 mm.) with shorter or longer marginal projections, sometimes with a few 

 low warts ; often the spicules disappear with age. Feet with end plate and 

 few perforated rods. Dorsal scales covered by a varying number of loose 

 grains. 



Type. — Paris. 



Type locality. — Patagonia. 



Distribution. — From Cape Horn to the southern part of Bering Sea. 



Depth. — In the Patagonian waters ranging from 7-207 fms. ; in the 

 northern waters taken between 155-603 fms. 



Specimens examined. — About 50 in the U.S.N.M. and Hopkins Ma- 

 rine Station from various Albatross stations. 



Remarks. — The specimens examined agree with Perrier's form seg- 

 regatus from Cape Horn except in minor points (equal development of 

 the gonads and slightly different position of the paired retractors, prob- 

 ably because of a different degree of contraction). The material has been 

 compared with the typical form from Norway and shows the same differ- 

 ences as those which Ekman has tabulated. 



Ludwig's P. pauper from the west coast of Mexico represents a small 

 specimen of var. segregatus in which the spicules in the sole are unusually 

 scarce. Ludwig's "antarcticus" from off Peru, which has always been 

 regarded with suspicion, is most likely a small specimen of segregatus (or 

 a specimen of Psolus patagonicus Ekman or of Psolidium ekmani). The 

 young individuals of P. squamatus, var. segregatus may superficially re- 

 semble either of these two forms. 



2. Psolus patagonicus Ekman 

 Plate 30, Fig. 8 



Psolus patagonicus Ekman, 1925, p. 140, text figures 35-36. 



Diagnosis. — Small form (sole up to 2 cm. long) with distinct oral 

 and anal valves and radial teeth inside the valves. Few scales between 

 oral and anal valves; often smaller scales intercalated between the pri- 



