OP SOUTHERN INDIA. 349 



4, AxiN^A SUBAURICULATA, Forbes, PL XVII, Pigs. 31-32e 



1846. Pectunculus suhauriculatus, Forb., Trans. Geol. Soc, Lond., vii, p. 150, pi. xvii, fig. 13 \—idem auctorum. 



Ax. testa sub-rotundata^ cdquilaterali^ paululum obliqua^ crassa, postice ad mar- 

 ginem sub'trtmcata, infra medium sub-angulata, tumida, radiatim costulata^ costulis 

 confertis ; areaparva^ valde declivi ; car dine dentibus elongatis, 9-10 in utro que latere, 

 et circiter decern intermediis, minoribus, instructo ; margine interno denticulato. 



Height of shell : its length ... ... ... ... 1-04 



Thickness „ : „ ... ... ... ... 0-68 



Distinguished from the next species by its rounder shape, smaller and more 

 precipitous area, and closer radiating ribbing. 

 Locality > — Kunnanore, in grey sandstone. 

 Formation, — Arrialoor group. 



5. AxiN^A CAEDioiDES, d'OrUgny, PL XVII, Pig. 33, PL L, Pig. 8. 



1847. Area cardioides, d'Orb., Yoy. Astrolabe, Paleont., pi. iv, figs. 35-36 ; — eadem auctorum. 



Ax, testa sub-rotundata, paulo longiore quam alta, tumida^ sub-cequilaterali^ 

 obliqua, postice pUis minusve distincter producta et sub4rtmcata, radiatim costulata, 

 costulis in declivitate antica et postica fere obsoletis, in medio sulcis aut cequidistan- 

 tibus aut angustioribus separatis, nonnunquam sub-granosis, ornata ; umbonibus pro- 

 minentibus, incurvis; area ligamentali magna, moderate declivi; cardine crasse et 

 pUciforme multidentato. 



Height of shell : its length ... ... ... 0-86 - 0"90 



Thickness „ : „ ... ... ... 076 - 0'78 



There are slight variations to be observed in the form and ornamentation of 

 this species. D'Orbigny figured a comparatively very inequilateral and oblique 

 specimen from Pondicherry ; we have exactly similar specimens from Ootatoor and 

 Odium, (see pi. 1, fig. 8). Another specimen from the same locality and one from 

 Serdamungalum out of a conglomeratic calcareous rock are somewhat less produced 

 posteriorly, and the radiating ribs are a little more distant from each other, than 

 is generally seen in Ootatoor specimens, but there is no appreciable specific dis- 

 tinction between the two forms. Although the shell is somewhat oblique, the dis- 

 tribution of the hinge-teeth clearly shows that it belongs to Axincea, 



Localities, — Pondicherry, Ootatoor, Odium, and south-east of Serdamungalum. 



Formations. — Ootatoor and Trichinopoly groups. 



ISO ARC A, Milnster, 1842, (see p. 338). 



1. IsoAECA GiBBA, StoUczha, PL VIII, Pig. 3, and PL XVII, Pig. 36. 



I. testa trapezoidali, valde gibbosa, tenui, sub-incequilaterali, antice rotundata, 

 postice paulo producta, oblique convexe truncata; umbonibus valde incurvis, approxi- 

 matis ; superficie minute reticulata vet decussata, striis filiformibus, concentricis , 



