OF SOUTHEEN INDIA. 355 



length, but it always does so in its thickness, the ligamental area becoming very 

 broad and rather closely angularly sulcated. In this stage some of the specimens, 

 as, for instance, the one represented in fig. 3 of pi. xx, are so remarkably like the 

 European Trig, Mather oniana, d'Orb., that I do not think their identity by any 

 means improbable, but unfortunately I have no typical specimens for comparison. 

 The hinge-teeth of Brahminica are also very similar to those of Matheroniana, 

 There are four or five oblique teeth on either side below the angle ; the median 

 hinge-teeth become very small towards the middle, sometimes they are nearly obso- 

 lete, the hinge-line itself being thin, and in this respect strongly differs from that of 

 Trig, Gamana, 



Localities,— NeiglihouTkoodL of Karapaudy, Arrialoor, Mulloor, Comarapol- 

 liam, &c., mostly in a coarse sandstone ; not very common. 



Formation,— Avvi^Xoov group, of which the species appears to be equally 

 characteristic, as is Trichinopolitensis of the Trichinopoly and Gamana of the 

 Ootatoor group. 



6. Trigonoarca Galdrina, d'Orbigny, PL XVIII, Eigs. 2—5. 



1847. Area Galdrina, d'Orb., Voy. Astrolabe, Paleont., pi. v, figs. ^2-^^—eadem auctorum. 



Trig, elongate trapezoidali, incequilaterali, moderate inflata, antice suh-rotundata, 

 postice carinata et valde producta, oblique truncata ; area mediocri, angulatim 

 striatO'Sulcata ; superficie concentrice filiforme striata; declivitate postica prope 

 medium latisulcata et striis radiantihus nonnullis, supra circiter 8, infra ad carinam 

 4-5, tecta ; cardo dentibus numerosis sicut in speciebus typicis instructus. 



Height of shell : its length ... ... ,,, ,., 0*55 



Thickness „ : „ ... .., ^^^ 0-48 



A markedly elongated form, slightly inequivalve, the left valve being a little 

 larger. The striae on the surface often become almost quite obsolete, in which 

 state the shell shows a great similarity to Trig, Gamana, being distinguished from 

 it merely by the more elongated form and comparatively less narrowed anterior 

 side. The posterior radiating ribs near the carina are very characteristic. 



Locality, — East of Serdamungalum and near Stripermatur, in a soft whitish 

 sandstone. 



Formation, — Arrialoor group. 



ANOMALOCARDIA, Klein, [SCAPHAECA, Gray, 1847] (seep. 339). 

 1. Anomalocardia [Scapharca] Ponticeriana, d'Orbigny, PI. XYII, Pig. 39, 



PI. XVIII, Pig. 1. 



1847. Area ponticeriana, d'Orb., Voy. dAstrolabe, Paleont., pi. v, figs. 29-31, — eadem auctorum. 



Scaph, testa valde elongata, tumida, antice oblique rotundata, postice sub-cari- 

 nata, declivitate prope medium sub-sulcata, ad terminationem oblique truncata, 

 incequivalvi, valva sinistra paulo majori ; superficie radiatim costulata, costulis 



4s 



