OP SOUTHEEN INDIA. 461 



4. ExoGYRA YK.v^Tk, Stoliczka, PI. XXXVIII, Eigs. 4—5; PL XXXIX, 



Pigs. 3 — 5. 



Ex, testa irregulariter ovato elongata aut sub-quadrata ; valva inferiore aut prope 

 umbonem, aut magna parte lateris ventratis^ sessili, gibboso convexa, prope medium 

 maxvme elevata, radiatim costata : costis sparsis, scepe dicJiotomis, tameltis concen- 

 tricis irregularibus interruptis, aut acute rugatis ; umbone modice prominuto^ valde 

 intorto, apice depressiuscuto, indistincto ; fovea tigamentati longa, angusta^ sub- 

 mar ginali^ curvata, ad apicem sulcum etongatum, dent em valv. alter ce recipient em, 

 carente ; impress, muse, late ovulata^ antice (vel supra) truncata^ haud procul 

 ab u/mbone sita ; marg, pall, pone terminationem fovecB ligam, breviter crenulato ; 

 valv, super lore undulate planata, concentrice sub-rugosa et ad marginem convexum 

 paulo incrassata et undulate lamellosa. 



The form of the shell of this species is very variable, the larger valve being 

 either only with a small portion of the beak sessile or with nearly the whole of 

 the lower half. According to the amount, or place, of attachment the gibbosity of 

 the larger valve is more or less regular. The surface is marked with compara- 

 tively few, irregular, often divided ribs, which are intersected by strong concentric 

 lamellae of growth, mostly prominent on the ribs. Near the margin the ribs 

 become obsolete or very nearly so. The smaller valve is usually somewhat undu- 

 lating, smooth or covered with a few concentric rugosities, and at the convex 

 margin it is always more thickened and lamellated. The only species which can 

 be compared in general character with the Indian fossil is Exog, Olisoponensis, 

 Sharpe, from Portugal (Coquand, Mon. Ostr. cret., p. 125), but in this species 

 the ribs are still less in number on the larger valve, and its beak is much more 

 prominent and more strongly spirally incurved. 



Locality, — Anapaudy, in a brownish sandstone. 



Formation, — Trichinopoly group. 



5. ExoGYRA COSTATA, Say, PL XL, Pigs. 1—3 ; PL XLI, Pig, 1. 



1821. 'Exogyra costata, Say, Am. Journ. Sc. and Arts, ii, p. 53. 



1834. E. costata et lOstrea torosa, Morton, Synop., pp. 50 and 55, pi. vi, figs. 1-4, and pi. x, fig. 1, 



1869. Ostrea torosa, apud Coquand, Mon. Ostr. cret., p. 38. 



Ex, testa rotundate ovata ; valva majore inflata, umbone valde intorto, later- 

 aliter sessili, concentrice lamellate striata et radiatim costulis irregularibus, confertis, 

 partim undulatis, scepe interruptis et dichotomis, ornata ; valva minor e plana, concen- 

 trice striata, nonnunquam costulis nonnullis radiantibus tecta ; impressione musculari 

 prope umboyies sita, excavata, transversaliter sub-ovata ; fovea tigamentati longa, pro- 

 funda, angusta, marginali, lente curvata, infra acute marginata et area rugulosa 

 sub-triangulari sub-posita, 



I can see no difference between specimens from South India and those from 

 North America; smaller and larger specimens perfectly agree in form, in the 



5 w 



