OE SOUTHEEN INDIA. 221 



striation is obsolete or nearly so on the anterior declivity, and tLe ribs on the 

 posterior declivity are numerous, close together and rather indistinct; near the 

 thickened fulcra they are as usual quite obsolete. 



The species has been first figured by d'Orbigny in the Paleontology of the 

 Voyage of the Astrolabe and Zelee, but subsequently (Prod, ii, p. 242,) the same 

 author considered it as identical with the next species, from which, however, the 

 distinctions become readily apparent by a comparison of the figures. 



Localities. — Anapaudy, Alundanapooram, &c. ; not uncommon. 



Formation. — Trichinopoly group. 



s/ 4. Peotogaudium altum, Sowerhy, PL XII, Eigs. 1 and 3. 



1846. Cardiujn alUim, Sow., apud Forbes, Trans., Greol. Soc, London, vii, p. 145, pi. 15, fig. 13 — idem auctorum. 



Frot, testa oMiqiie siib-trigonata^ crassa, altiore quam longa, moderate inflata, 

 lunula paulo excavata, antice et infra ad marginem rotundata^ postice sub-truncata^ 

 margine postico superiori oblique descendenti, recto ; superjicie lamellose costulata^ 

 costis in parte antica obsoletis interdumque lineis filiformibus radiantibus substitutis ; 

 costulis in declivitate postica sitis confertissimis, inferioribus magis distinctis quam 

 superioribus. Cardo dentibus crassis regularibus instructus. 



Height of sMl : its length ... ... ... TIO - 1-20 



Thickness „ : „ ... ... ... O'SO - 0*85 



In this species the concentric lamellar ribs are about the middle of the shell, 

 obsolete on a larger area than in the last, and moreover they are sometimes replaced 

 by more or less distinct, but usually very fine undulating radiating striae. The lunula 

 is somewhat excavated, and the posterior hinge line particularly straight and 

 descending. The shell is, as already stated, more oblique and higher than the last 

 species, while the smaller extension of the posterior area readily separates it from 

 Frot. bisectum. 



Locality. — Monglepaudy, Odium, Ootatoor ; not common. 



Formation, — Ootatoor group. 



v/ 5. Protocauditim bisectum, Forbes, PL XII, Eig. 2. 



1846. Card, bisectum, Forh., Trans., Geol. Soc., London, vii, p. 144, pi. 17, fig. 9— idem auctorum. 



Frot. testa multo altiore quam longa, valde inflata, moderate crassa, umbonibus 

 valde prominentibuSy incur vis, fere contiguis, angustis, antice lemter convexa, postice 

 truncata ; margine posterO'inferio?^ moderate producto, lunula paulo excavata ; 

 superjicie in dimidio antico concentrice subtiliter striata^ in postico radiatim 

 costellata. 



HeigM of sliell : its length ... ... ... 1'40 



TMckness „ : „ ... ... ... 1'13 



The great height of the shell in proportion to its length, and the whole of the 

 posterior half of the surface being occupied by radiating ribs, readily distinguish 



3 H 



