146 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 8 



lacrum. Dorsal side with smooth imbricating scales, gradually decreasing 

 in size around the oral and anal openings; tube feet few, small, easily 

 overlooked. Entire dorsal surface covered by numerous large grains and 

 other deposits, easily rubbed ofif. 



Spicules in sole an external layer of delicate smooth 4-holed flattened 

 cups with marginal teeth. Beneath these a few larger plates may be found 

 with several holes and smooth to undulating surface. Dorsal side closely 

 packed with thimble-shaped grains with flattened basal plate (i.e., short, 

 squat towers), besides numerous small baskets with delicate teeth and 4 

 apical knobs, sometimes united to a ring, thus approaching the hourglass 

 shape. Tube feet with delicate end plate and circular or squarish curved 

 supporting plates. (Tentacles not examined.) 



Type. — Holotype, AHF no. 40. 



Type locality.— Station 845-38, Sechura Bay, Peru, Lat. 5° 39' 30'' 

 S.; Long. 81° 01' W., 9.5 fms., February 15, 1938. 



Distribution. — From Peru to Colombia. 



Depth. — From 9-60 fms. 



Specimens examined. — The following specimens from the Hancock 

 Expeditions : 

 845-38. Sechura Bay, Peru, coarse sand, worm tubes, red algae, 9.5 fms., 



February 15, 1938, 3 specimens. 

 854-38. Gorgona Island, Colombia, north of island, mud, rocks, 40-60 

 fms., February 24, 1938, 1 specimen. 



Remarks. — The species has been referred to Psolidium because the 

 cups in the dorsal integument are mostly simple and the feet on the sole 

 are few. The dorsal spicules are easily rubbed off, but the spicules in the 

 sole are so characteristic that it seems impossible to confuse it with any 

 other species. 



Genus 3. PSOLUS Oken, 1815 



Diagnosis. — Typical psolids with distinct sole with marginal tube 

 feet, often also a band of feet along the midventral ambulacrum. Dorsal 

 side covered by scales, few to many ; oral and anal apertures with or with- 

 out an operculum of triangular scales ; sometimes narrow radial teeth 

 present inside of and between these valves. No appendages on dorsum 

 except the anal papillae and in some forms a few tube feet on the intro- 

 vert. Tentacles 10 in number, the 2 ventral may be smaller; in some 

 deepwater forms the tentacles are unbranched, finger shaped. Inner 



