246 BULLETIN "36, UNITED STATES NATIONAL MUSEUM, 



tlie second paired inferomarfrinal. There may be as many as twenty intermediate 

 plates in each angle, althoujrli the type has only two or three. One to four pecti- 

 nate pedicellariie with five to seven spinelets in each comb occur on each inter- 

 radial area of the example from station 2919. The type has only one pedicellaria 

 to an area. The plates have besides one or two spinules. 



Madreporic botly convex, prominent, circular, with coarse irregular.centrifugal 

 striations. It is situated one-half to more than its own diameter from the odd 

 superomarginal plate. 



Variatiom. — Only three large specimens are available, the type which lacks 

 the distal portion of all the rays, and two examples from station 2919. The 

 latter (one with one entire ray) have a considerably larger disk and larger actinal 

 intcrradial areas than the type as well as more extensive papular areas on the 

 ray. The rays are also wider at base. But a third specimen from the same 

 station has a disk relatively the same size as type, and papular areas which extend 

 only to the fifth superomarginal. The type is possibly a more immature indi- 

 vithial, which would account for the difference in development of disk, actinal 

 intermediate plates, and papular areas (to eighth superomarginal). The absence 

 in one interradius of the intcrratlial unpaired marginal (of both series) is of interest. 

 One superomarginal in this interradius is slightly larger than its neighbor and 

 coiTesponds to the odd plate. In Benthopecten mutahilis the odd plate is frequently 

 absent; and indeed in the type of the genus, B. spinosus it is also sometimes absent, 

 as a full-grown specimen from station 2711, off Cape May, has paired plates in 

 two interradii. Variations in adambulacral spines, and in occurrence of pedi- 

 cellarise have alreadv been alluded to in the description. A young specimen 

 with R about 50 mm. lacks pedicellarise entirely. There are six prominent disk 

 spines, of which the central is largest. The central slender spinule of the other 

 abactinal plates is characteristic, differing markedly from the minute spinelets 

 of clariger or the stubby granuliform tubercles of mutahilis. In these young the 

 raj's have a hirsute appearance. Another specimen, but a trifle larger, has 

 inferomarginal but no abactinal pedicellarise. It is interesting to note that a 

 very small example (R=ll mm.) has two inferomarginal pedicellarise, with twice 

 three or twice four spinelets, in each interradius; but there are no prominent 

 abactinal spines and no abactinal pedicellariEe. There are five prominent inter- 

 ratlial superomarginals and spines. There is but one furrow spine. An example 

 with R = 70 mm. has abundant abactinal and the usual number of inferomarginal 

 pedicellarise. 



Type.—C&i. No. 22330, U.S.N.M. 



Type-locality. — Off San Diego, California (longitude of Point Conception), 

 1,0,59 fathoms, mud. 



DiMnbution. — Southern California; 984 fathoms to 1,059 fathoms. 



Specimens examined. — Seven, the type, and six from station 2919, off Cortes 

 Bank (west of San Diego), in same general locality as that of type, 984 fathoms, 

 gray mud. 



IRemarks. — This is a vaiiable species, especially in the extent of the papular 

 areas, size of disk, and number of abactinal accessor}' spinelets. The type is probably 



