547 



the median radial plates, and in number of papulae surrounding them; 

 in covering of marginal plates; in having thicker specialized ridges to 

 inferomarginals, with correspondingly narrow fasciolar furrows; in the 

 special spinelets on both series of marginals which are robust and blunt 

 never slender or sharp; adambulacral spines 4, 5, or 6, flattened with 

 broad side to furrow (not compressed with edge to furrow as in eximius). 

 Bering Sea, north of Unalaska Island, 350 fathoms. Bottom, mud. 



Dipsacaster laetniophilus new species. 



With the characters given in the key, above. 



Between Unalaska and Kadiak, 695 fathoms. Bottom, mud. 



This species differs from D. nesiotcs Fisher (Hawaii) in having much 

 broader rays, longer paxilla pedicels in proportion to width of crown of 

 spinelets; more distantly spaced abactinal plates; marginals which 

 correspond plate for plate and to not alternate on outer part of ray ; 

 wider superomarginals and inferomarginals; a less plane actinal surface 

 to inferomarginals; less thick specialized ridge; broader fasciolar 

 grooves; more pominently carinated actinal intermediate plates; larger 

 actinal intermediate areas on rays. 



Dipsacaster anoplus new species. 



With the characters given in the key, above. 



Off Cascade Head, Oregon, 345 fathoms. Bottom, mud. 



This species resembles a Leptychaster of the anomalus-pacificus 

 form but can at once be distinguished by the characteristic arrangement 

 of gonads, which, as in all species of Dipsacaster ^ extend far along ray 

 on either side, as independent tufts attached to the genital stolon. 



Bentliopectiuidae. 



Beiithopecten Verrill. 



The species occurring off the west coast of North America are con- 

 trasted in the following key; 



a. Inf eromarginal plates with pectinate pedicellariae at base 



of ray only; or if occurring beyond middle of ray, actinal 

 spinelets davate (bbj. Odd interradial marginal plates 

 normally present in all interradii. Actinal interradial 

 areas small. 



b. Abactinal plates of ray with only 1 slender central 

 spinule; abactinal pedicellariae numerous on ray ex- 

 tending nearly to tip ; actinal and inferomarginal spines 



of proximal part of ray not davate . . B. acanthonotus Fisher. 



35* 



