39 



Basal plates very much depressed, anchylosed, and form a pen- 

 tagonal disc, less than twice as wide as the diameter of the col- 

 iimn. Subradials, the largest plates in the calyx, hexagonal, longer 

 than wide, almost wholly within the basal coQcavity, and not vis- 

 ible in a side view. First radials rather smaller than the subradials, 

 heptagonal, about as wide as long, rest on the outer rim of the 

 truncated base of the calyx, and each one bears a long, slender, 

 central spine, which, by reason of the position of the plate, is 

 directed downward, at an angle of from thirty to forty- five degrees, 

 and on the points of which the calyx may be made to stand. 

 Second primary radials smaller than the first, longer than widef 

 hexagonal, inferior lateral the longest and each one bears a long 

 central spine directed horizontally. Third primary radials less 

 than half the size of the second, and longer than wide. This is as 

 far as the plates are preserved in the two larger specimens, which 

 we have illustrated, and that far they seem to agree with the 

 smaller specimen. The interradial areas to this height appear to 

 agree substantially with (7. (jrccnci. Two of the interradial areas 

 are lilie the one represented in Figure 18 and three of them are 

 like the one represented in Figure 19. From this point to the 

 summit we will look at the small specimen and note how it differs 

 from G. greenei. The plates in the intersecondary aud interradial 

 areas are anchylosed, but the intersecondary areas are pioportion- 

 ally longer and the interradial areas shorter, and hence, it would 

 appear, that there are more plates in the intersecondary areas in 

 tbis species than in G. greoiei, but this is estimating on space, 

 and if we could see the plates, their size might govern instead of 

 space. 



The vault, however, is (^uite different in this sjaecies from what 

 it is in (f. (jreeiiei. The vault is covered, in this species, by 

 minute, almost granular convex plates, which gives it quite a dif- 

 ferent aspect. Although the specimen is much smaller, the plates 

 are at least fifty per cent, more numerous, in this species than in 

 that. The interradial areas are much more depressed .and the 

 ovarian canals (if it be proper to call them by that name) project 

 much farther beyond the margin of the calyx, in this species than 

 they do in G. (jreenei, and they are proportionally larger, and 

 occupy more space between the ambulacral openings. The vault 

 of our specimen preserves part of the a/.ygous apertures which 



