24 
CRETACEOUS ECIIIXODERMATA 
1. IIoLASTER INDICES, Forbcs. PI. IV, Pig. 5. 
‘ H. cordatus, injlatus, postlce editor, exlrcmUcde anedi obtuse rostreda, infra 
‘ spaiio poslorali convexa, snbearinata. 
‘Length inch. Breadth 1^- inch. Greatest height 1 inch. 
‘ Very regularly heart-shaped, nearly as hroad as long. Back most convex 
‘ posteriorly in the space between the two postero-lateral ambulacra. Behind, the 
‘ highest part of the body contracts a little as if jjinelu'd in, and is narrowly trun- 
‘ cated at the anal extremity. The anterior extremity is deeply cordate. The series 
‘ of pores forming the ambulacra gently diverge, and almost all nearly equally. In 
‘each scries of the four dorsal ambulacra there are about twenty-foiu* pairs of open 
‘ pores, the last five being jdaced distant from each other. The pairs of the several 
‘ series are not connected by grooves. The anal area is A’ertically oblong. On the 
‘ under suiTace the most prominent part is the post-oral space, vEicli is oblong, very 
‘ com'ox, and has a tendency to carination. The antcro-latcral portions (cheeks) 
‘ arc rather tiunid. 
‘ The nearest allies of tliis species arc the Uolaster snborbicidaris from the 
‘ upper chalk of Maastricht and equivalent formations. That species, however, has 
‘ the apex of the hack in the region of the ocelli. The Indian species has a nar- 
‘ roAver anterior groove. It is also allied to the Uolasler V Ilardyi of the Ncuchatel 
‘ greensand, hut differs in the disposition of the ambulacra.’ 
Family, — CAS SIT) FLIDJE. 
See De.sor, Synops. Echinid. foss., p. 245. 
The Cassidulid^, as arranged by Desor, include Echinoids of moderate or 
rather large size, variable in shape, round or polygonal, convex above, flat or 
slightly concave below, covered with small, mostly imperforated, tubercles, 
surrounded with rather deep areolae, small above and usually larger below ; the 
apex and mouth arc very variable in position, very often suh-central or cxccntric, 
the former composed of four genital and five ocular plates, the latter angular or 
pentagonal, surrounded Avith lobes or not ; ambulacra petaloid or suh-petaloid, 
sometimes nearly continuous, hut not situated in depressions, the petala being open, 
though always somcAvhat contracted towards their ends, they are all of equal or 
very similar "shape ; the poriferous zones* often re-appear better marked near the 
peristome of the mouths ; no jaAVS are present ; the position of the anus varies be- 
tween supra-marginal, posteriorly terminal, or infra-marginal ; the spines are mostly 
thin and small, longitudinally striated. 
* The name buccal roBettc or floscellc has been proposed by Desor for the oral ambulacra in connection with 
the oral lobes. 
( 94 ) 
