218 BULLETIN 76, UNITED STATES NATIONAL MUSEUM. 



similar to those of abactiiial surface stand on the superomarginals. The plates 

 of the two series do not exactly correspond, the lower edge of the superomarginals 

 beinf, in consequence, frequently angular. Superomarginals fourteen, infero- 

 marginals sixteen to the ray. 



Inferomarginals are about the same size as the superomarginals, but the 

 ilistal ones decrease rcgvdarly in size, and the last four or five have a tumid bare 

 spot. The granulation is the same as on the upper series, and a pedicellaria is 

 sometimes present. The marginal plates are about as small as in lej)toceranius. 

 In a small specimen from southern California, very doubtfully referred to this 

 species, the marginals are slightly larger, are all wider than long, and the distal 

 superomarginals are not enlarged. 



Adambulacral plates narrow, slightly longer than wide, with a furrow series 

 of four or five (sometimes six), distally three, equal, rather long, compressed, blunt 

 spinelets. These are considerably longer than width of plate and longer even 

 than the length of plate. The two median spinelets are freciuently more com- 

 pressed than the laterals. Immediately behind the furrow spinelets is a longitu- 

 dinal parallel series of two or three much stouter, cylindrical, blunt, tubercular 

 spinelets about two-thirds the length of the furrow spinelets. Proximally these 

 spinelets are often compressed and quadrate in section. Far along the furrow 

 there are two in the series, and the adoral is reduced in size, the aboral becoming 

 conspicuous and equaling the furrow spinelets in length. The outer margin of the 

 plate is occupied proximally by an irregular row of three to six bluntly pointed 

 granules; distally there are two rows or a group. The adambulacral plates, far 

 along furrow, gradually become square. 



Mouth plates large, rather plane, with a long margin to furrow bordered by 

 about ten spinelets, increasing slightl}^ in size toward the inner angle, the innermost 

 spine being strongly compressed and leaf -like, and those adjacent three-sided in 

 section. About eight shorter, blunt, irregular, tubercular spinelets form a parallel 

 series wliich is continued along the first adambulacral margin. On the outer part 

 of the plate three or four elongated granules stand close to the median suture 

 (which is not visible), and the series of spinelets just mentioned may be (;ontinuous 

 with these instead of with the spinelets standing on margin adjacent to adambu- 

 lacral. 



Actinal intermediate plates numerous, but the sutures are not readily seen. 

 The series of plates adjacent to adambulacrals are not larger than the next series, 

 are obliquely elliptical in general form, but have several sides. The other plates are 

 elliptical or irregularly rhombic, sometimes rouncUsli. They have not the straight- 

 cut sides found in granulans, japonicus, and jMtagonicus. In the previously men- 

 tioned young specimen from southern California the plates are much more regular; 

 it is possible that the irregularity comes with age. The plates bear spaced, large, 

 hemispherical granules, those occupying the margin being sensibly smaller and 

 more or less pointed. Many of the plates adjacent to the adambulacrals bear a 

 conspicuous pedicellaria, with two oblong, shghtly spatulate, round-tipped, or sub- 

 truncate jaws. Near the margin many plates have a similar but smaller pedicellaria 

 with two or three jaws. The granulation is much coarser than in leptoceramus, 

 where the granules are also spaced and uniform in size. 



