M8 OEETACEOUS PELEOTPODA 



front area apparently somewhat excavated ; towards the margin the valve is free, 

 obliquely elevated, radiately striated, and concentrically strongly lamellated. The 

 upper valve is moderately convex, covered with very numerous radiating ribs, which 

 are of sub-equal size and made sharply rugose by the concentric striae of growth ; a 

 few of the radiating ribs are stronger, and armed with laterally compressed, tuber- 

 culous spines. The ears are rather large, almost equal, nearly smooth, with straight 

 thickened hinge margins, near which runs a strongly foliaceous or spinulose rib; 

 the beak is obtuse and slightly projects beyond the hinge margin ; (the last two 

 characters are not suflS.ciently clearly shown in the figure). 



Locality, — -South-west of MuUoor, in soft grey sandstone. 



'Formation, — Arrialoor group. 



2. Spondylus sulcatellus, Stoliczka, PL XXXIV, Eig. 1. 



Sp, valva superiore oblique ovata^ moderate convexa, irregulariter undulate 

 rugosa^ radiatim dense costellata, costellis lateraliter compressis^ rugulis, sulcis pro- 

 fundis (Bquidistantibus separatism hie et illic tuherculis crassis^ squamiformibus in- 

 structis ; umbone depresso ; auriculis sub-cequalibus^ radiatim costellatis ; lunula 

 angusta et profunda. 



The irregular undulations on the surface of the upper valve seem to be, to a 

 certain extent at least, characteristic of this species, and have probably been pro- 

 duced by the shell having been sessile on corals, to which fragments have been 

 found attached. The most marked character of the species consists in the radiating, 

 sharp, laterally compressed ribs, these being separated by deep furrows, in thickness 

 equal to the ribs ; a few strong tubercles occur on their surface, but the ribs 

 themselves are not thickened. 



Locality. — North of PoodoopoUiam, in a white earthy limestone. 



Formation, — Arrialoor group. 



3. SpoNDYLrs CALCARATUS, Forbcs, PL XXXIII, Eigs. 6, 7, 9, and 10. 



1846. Spondylus suhsquamosus et calcaratus, Forbes, Trans., Geol. Soc, Lond., vii, pp. 154-155, pi. xviii, 

 figs. 1-2. 

 SjpondyUis calcaratus, auctorum. 



Sp, testa crassa, oblique late ovata ; valva inferiore multo majore, tumida^ 

 umbone valde extensa, nonnunquam conoidea^ torta, ad terminationem affixa^ trun- 

 cata; superficie libera radiatim costulata: costulis cequalibus^ planatis^ lineis impressis 

 angustis separatism concentrice crasse lamellosa : lamellis partim continuis, partim 

 interrupts ; area longa, sub-trigona, longitudinaliter obsolete striata et medio sulco 

 sub-angustato instructa ; valva supera planO'Convexa, ad umbonem scepe gibbosula, 

 radiatim costulata et concentrice striata, costulis aut paucis aut numerosis, crassi- 

 oribus tuberculis transverse squamiformibus ornatis ; auriculis incequalibus, postica 



