548 



bb. Abactinal plates of ray proximally with 1 spinule and 

 several minute spinelets ; beyond papular area with 1 to 

 several minute spinelets; proximally the actinal and 

 inferomarginal spines davate; abactinal pedicellariae 

 usually confined to disk and base of rays B. claviger new species. 



aa. A majority of interradii usually without odd interradiais, 

 and inferomarginals with pedicellariae nearly to tip of 

 ray. A few prominent spines on center of disk, the 

 others short and stubby, robust. Interradial areas 

 larger B. niutabilis new species. 



Benthopecten claviger new species. 



Rays 5. E, 110 mm; r 12; R 9,1 r. Breadth of ray at base, 14 mm. 

 Disk small, rays long and evenly tapering; interradial angle abrupt. 

 Abactinal surface of disk with numerous conspicuous thorny-surfaced 

 spines which extend into rays for a short distance, these surrounded at 

 base by 8 to 15 or even more very small thorny spinelets; numerous 

 intermediate plates with 1 to 5 tiny spinelets ; on ray plates with 1 to 5 

 similar spinelets forming a fine nap. Interradial odd superomarginal 

 very prominent. Abactinal pectinate pedicellariae present but usually 

 variable in number. Inferomarginal and actinal adambulacral spines 

 of proximal part of ray club-shaped, the former 2, the latter 2 (some- 

 times 3j in number. Furrow spines 4 to 6, slightly curved. Pectinate 

 pedicellariae between proximal inferomarginals, rarely farther along ray. 



Off Cape Blanco, Oregon, 1064 fathoms. Bottom, green mud. 



The most characteristic features of this species are the davate 

 actinal and inferomarginal spines, the prominent thorny disk spines, and 

 the extremely delicate abactinal spinelets which often are exceedingly 

 small. B. spinuliger (Ludwig) differs in lacking the prominent spines of 

 disk, in having numerous (13 — 16) marginal mouth spines, and in lack- 

 ing the characteristically formed actinal spines. 



Benthopecten mutabilis new species. 



In general appearance similar to B. spinosus Verrill but usually 

 lacking some of the odd interradial marginal plates (always in one or 

 the other series, as a rule in both) ; abactinal, actinal intermediate and 

 inferomarginal pedicellariae, the latter series extending to tip of ray, 

 the first extending far along ray , as a rule ; (pedicellariae lacking in B. 

 spinosus). Abactinal surface with several large spines near center of 

 disk, each usually surrounded by several small spinelets; other plates 

 of disk with 1 to 3 or 4 very short stubby spinelets , and plates of ray 

 with typically 1 such spinelet. Superoraarginals with 1, inferomarginals 



