340 BULLETIN lOO, UNITED STATES NATIONAL MUSEUM. 



Superomarginals, 30 in the type, are not at all tumid, and form a 

 slightly arched bevel, the first 5 or 6 slightly wider than long; the 

 succeeding 12 to 14, longer than wide; and the remainder gradually 

 becoming wider than long. They decrease very gradually in width, 

 irrespective of the changing length, and are covered with spaced 

 minute granules, with 5 or 6 spaced coarse hemispherical granules 

 oil the center of the first 4 or 5 plates. These are the only granules 

 that show through the membrane, as a rule, although there is varia- 

 tion in this respect. Usually the plates feel smooth to the touch, 

 the gi'anules not being so evident as in granulosus or lithosorus. 

 This is particularly true of the medium-sized and small specimens. 

 In some of the largest specimens the proximal plates have 1 or 2 

 small spatulate 2- jawed pedicellariae, but these are present in less 

 than half of the specimens. Terminal plate pentagonal from above, 

 with 5 terminal spines. 



Inferomarginals extending laterally slightly beyond the supero- 

 marginals, the actinal face wider than long at base of ray, gradually 

 becoming longer than wide at the middle. They are covered with 

 spaced, rather unequal, granules coarsest on the margin (and these 

 about as large as the largest superomarginal granules), decreasing 

 in size toward the inner margin of plate. The plates are narrower 

 than in lithosorus^ but the granules are of nearly the same relative 

 size, perhaps a little smaller. 



The actinal intermediate plates extend to the twelfth inferomar- 

 ginal or a little over half the length of ray in large specimens, and 

 are covered with spaced, coarse, hemispherical granules, 3 to 10 in 

 the center being the largest, and the others of several smaller sizes, 

 as in granulosus and Uthoso^nis. A variable number of proximal 

 plates of the series adjacent to the aclambulacrals bear 1 or 2, or 

 occasionally as man}^ as 6 forcipiform pedicellariae. In this type 

 these are very few, but a specimen from station 5260 has many. 

 Some examples (as station 5501) have the pedicellariae intermediate 

 between the bivalved and forcipiform types, just as the abactinal 

 pedicellariae vary. In the example from station 5260 the granules 

 on the inner chevron of plates tend to become pointed and spiniform. 

 In the large and small alcoholic specimens the outlines of the actinal 

 intermediate plates are usually visible, but not in the medium-sized 

 examples where, also, the central granules are less prominent than 

 in the largest specimens. In the latter, the central granules appear 

 as spaced clusters overlaid by membrane, the smaller granules being 

 inconspicuous or invisible until dried. 



Adambulacral plates similar to those of granulosus but more vari- 

 able as regards the subambulacral armature. Furrow spines stout, 

 compressed, of nearly uniform width when viewed from above, but 



