466 CRETACEOUS PELECYPODA 



fine radiating lines, but there are very rarely any ribs to be observed on tbe larger 

 valve. Erom its close ally, GrypJi. probosciOea, d'Arcb., tbe present species is 

 distinguished by the greater development of the ligamental area and the marginal 

 lobe, while in prohoscidea the furrow, separating the last, is more median. The 

 globosity, or gibbous form, of the larger valve is, however, not a reliable character 

 for distinguishing the two forms, and young specimens of both are often very 

 difficult to separate. 



Localities. — Comarapolliam, Arrialoor, Ninnyoor, in whitish sandstone. 



Formation. — Arrialoor group. 



G. vesicidaris is a characteristic fossil of the upper cretaceous beds (Campanien 

 of Coquand) ; it has been found almost throughout Europe in these beds, as 

 well as in North America, Algiers, Syria, and Asiatic Russia. 



5. GRTPHiEA VESICULOSA, Sowerhy, PI. XXXIX, Eigs. 1 — 2. 



1823. Gryphma vesiculosa, Sow., Min. Conch., vi, pi. 369. 



1869. Ostrea vesiculosa, apud Coquand, Monog. Ostr. cret., p. 152. 



Gryph. testa aut ohlonga ant irregulariter siib-rotundata ; valva ivferiore tmnida, 

 valde convexa, siih-lcuvigata, striis incrementi tenuissimis tecta, libera aut prope 

 nmbonem sessili, indistincte lobata interdmnqiie parte infero-posteriore sensim pro- 

 ducta, imibone siib-acuto, incurw vel trimcato ; area Ugainentali lata, medio modice 

 excavata ; impress, muse, siib-ovata, excentrica, postero-inferiori, paxilo profunda ; 

 impress, pall, ad ttmbonem wijjressa, indistincte plicatula, (valvam minorem, Icetiga- 

 tam, concaviusculam non vidij. 



This species differs from the previous by its smaller size, thinner shell, more 

 tumid and very indistinctly or not at all lobed larger valve, and the almost smooth 

 pallial impression, &c. It is also a geologically older form. 



Localities. — East of Poodoor and north-east of Odium, in a whitish friable 

 calcareous rock ; only one specimen was found at each of the localities. 



Formation. — Ootatoor group. 



G. vesiculosa characterizes the middle cretaceous beds, the Rotomagien of 

 Coquand. It was found in these beds (Upper Greensand) in England, in Erance, 

 Belgium, Germany, Bohemia, Switzerland, and in Syria. In India it also occurs 

 with Amm. Botomagensis, Lnoceramus mytiloides, Exogyra canaliculata, 8fc. 



OSTREA, Linne, 1738, (see p. 453). 



1. Ostrea [Alectbyonia] diluviana, Linn4, PL XLVI, Eigs. 1 — 2 ; PI. XLVII, 



Eigs. 1—2. 



1767. Ostrea diluviana, Linn^, Syst. nat., p. 1148. 



1846. Ostrea pes-leonis, Forbes, Trans. Geol. Soc, Lond., vii, p. 156, pi. 18, fig. 5. 



1869. Ostrea diluviana, apud Coquand, Mon. Ostr. cret., p. 120, cum. sj'n. 



Ost. [Alectr.] testa irregulariter ovata aut sub-tetragona, suh-a;quivalvi ; valva 

 inferiore paulo majore, plus minusve latiuscule affixa, utraque radiatim costata : 



