192 



VERRILL 



ones are a little stouter and less acute, mostly not quite so long. 

 They usually bear a small group of minor pedicellariae on the outer 

 side. 



The inferomarginal spines mostly stand two or three to a plate, 

 forming a pretty regular double row. They are much stouter than 

 the adambulacrals and not quite so long ; many are a little flattened 

 or pinched up at the tip, and often slightly gouge-shaped. 



The superomarginals are more numerous and shorter, of similar 

 shapes. Near the disk they often stand four to six on a plate, 

 crowdedly. There are no peractinal plates. Major pedicellariae are 

 numerous on the sides and actinal surface. The larger of these are 



FIG. 8. 



Allastcrias rathbiini nortonensis Ver. No. 7621, U. S. Nat. Mus. Spines; a, intra-ambu- 

 lacral; b, outer-adambulacral ; c, inferomarginal. X 20. 



elongated, acute or acuminate in profile, with the valves mostly 

 narrow spatulate ; some of them are dentate at the tips, with two or 

 three curved teeth. The larger ones measure 0.67 mm. X 0.30 mm. ; 

 0.67 mm. X 0.27 mm. ; 0.65 mm. X 0.25 mm. ; 0.57 mm. X 0.23 mm. 

 Many are smaller, short and thick, sometimes as broad as long. 

 These measure 0.50 mm. X 0.30 mm. ; 0.40 mm. X 0.27 mm. ; 

 0.35 mm. X 0.40 mm. ; and smaller. 



The type, and the only specimen seen, was from Norton Sound 

 (coll. Murdoch, No. 7621, U. S. Nat. Mus.). This presents several 

 rather strongly marked characters, which might be considered 

 specific if persistent in a large series of specimens. But with the 

 small number of specimens available for study it seems better to 

 consider it a subspecies at present. Very likely the species may prove 

 to be a very variable one. The characters that seem most important 

 are the smaller size and stouter form of the major pedicellariae, and 



