ASTEBOIDEA OF NORTH PACIFIC AND ADJACENT WATERS FISHER. 



77 



seven furrow spinelets. Actinal interradial areas are smaller than in large exam- 

 ples, the plates extending about one-half length of ray. Both the upper and lower 

 edge of ray is rather abrupt, not the u])per alone as in adults. Tiie epiprictal cone 

 is scarcely more prominent than in adult. 



Type.— C&t. No. 22327, U.S.N.M. 



Type-localitjf. — Albatross station 4387, off San Diego and southeast of San 

 Clemente Island, California; 1,059 fathoms, mud. 



Distribution. — Bering Sea to Bay of Panama," in 1,033 to 1,025 fathoms, on 

 green ooze, green mud, sand, and hard bottom. 



Specimens examined. — Total number, one hundred and nineteen, from the 

 following stations; six specimens have no label. 



Specimens of Psilaster pectinatw examined. 



Remarks. — This species has the general appearance of a long-spined Bathy- 

 iiaster, but the character of the abactinal plates, adambulacral armature, and 

 rather deep marginal fascioles assigns it to Psihster. The double row of infero- 

 marginal and single row of superomarginal spines is very similar to the arrange- 

 ment of the much smaller spinelets in Bathybiaster, and the actinal spinulation is 

 decidedly sacculate. It was these considerations which led me to describe the 

 species under Bathybiaster. Since then, however, I have seen an abundance of 

 material of this species and have examined Bathybiaster vexillifer and B. robustus. 



The character of the adambulacral armature is the most tangible feature which 

 separates the two genera. Both may have sacculate actinal spinelets, but Psilaster 

 has not the very angular furrow series with an elongate median spine bearing, 

 sometimes, a terminal flaj) of integument. The marginal spinules of Bathyhiaster 

 are very inconspicuous and the vertical fascioles along the suture between the 

 plates are decidedly shallow. 



Ludwig classifies this species in Plutonaster, a course which seems to me wholly 

 untenable, since it must necessarily ignore the sum of the structural characters in 

 favor of the presence of an anus. This is a good example of the bizarre results 

 which follow adherence to the erroneous idea that Astropectinida? lack and "Archas- 

 teridie" possess an anus. It is also an instance of the fact that the presence or 

 absence of an anus is not even of generic value. It does not seem logical to ignore 

 all of a half-dozen important skeletal and anatomical features in favor of a single 

 oft disjpialified character. 



Tliis species is readily distinguished from those described by Sladcn, by the 

 presence of one or two prominent superomarginal spines forming a regular series 



o Plutonaster abyssicola= Piilaster pectinatus. 



