OP SOUTHERN INDIA. 79 



PHOLADOMYA, Sowerbij, 1823 (see p. 70). 

 1. PHOLADOMYA CAUDATA, Bomer, PI. II, Pigs. 10-11, and PL XVI, Pig. 19. 



1839. Corbula (pqidvalvis, Goldf., Pet. Germ., pi. 151, fig. 15 (non Ph. (equalls, seu aquivalvis, Sowerby, 1823, 



Pusch, &c.). 

 1841. Pholadomya caudata, Romer, Ver.st. Norddeutsch. Kreidegeb, pi. 10, fig. 8, non Gon. (or Ph.) caudata, 



Ag., 1842). 

 1843. Pholadomya caudata, Romer apud Geinitz, Kieslingswalda, pi. 1, figs. 28-30, — jt/e;« Reuss. 



1845. Cardium caudatum, Romer, Bronns' Jahrb. f. M. und Geol., &c., p. 388. 



1846. Poromt/a cequivah-is, Forbes, Trans., Geol. Soc, Lend., vii, p. 141; — {idem Bosquet in Staring's Bodem 



van Nederlands). 



1846. Cardium lucerna, Forbes, Trans., Geol. Soc, Lond., vii, p. 145, pi. 17, fig. 10. 



1847. Cardium caudatum, d'Orbiguy, Pal. de la voy. d'Astrolabe et Zelee, pi. 4, figs. 25-26. 

 1847. Cardita Goldfussi, MuUer, Petref. Aachner Ki-eidef., pt. i, p. 20. 



1849. Pholadomya caudata, Geinitz, Quadersandstgeb., p. 148. 



1850. „ „ d'Orbigny, Prod, ii, p. 234, — (*We>» Ryckholt and others). 

 1865. „ cequivalvis, „ Pict. and Camp., Pal. Suisse, 4me ser., 3™^ pt., p. 94. 

 1867. „ caudata, Rom., Eiohwald, Leth. ross., 11™« livr., p. 769. 



Ph. testa ocalo-ohlonga, teiiul, tnmkla, sub-incequilaterali, cequivalvi (.''), postice 

 paiilo longiore, subccmdata et anguste hiante, iimbouibiis latis, incurcis mstrueta, in 

 saperficie cosfiilis tenuibm, crenulatis, (equalibus, radiant Ibus, confertis, in parte 

 postero-superiori obsoletis sed lineis pitncturatis substltutls notata ; cardine in valca 

 sinistra lamina unica bred, in valca dextra duabus infra umbonihus sitis fossa 

 mediana separatis instructo ; fulcris Ugamenti parvis. 



Height of shell : its length ... ... ... ... 0-77 



Thickness „ : „ ... ... ... ... 0-76 



The shell is always strongly tumid, inequilateral, the posterior half being 

 slightly longer, gaping, but rounded on both ends ; the beaks are thick, prominent, 

 and strongly iucuiTed. The surface is covered with very numerous, equal, radiating 

 and finely granulated ribs, except on the ujiper portion of the posterior end, where 

 only a few radiating punctured lines are traceable. It was most probably on account 

 of tliis punctured sm'face that Prof. Porbes thought the species to be a Poromya, 

 but the small single lamina below the beaks of the left valve fitting in a groove of 

 the other, or rather in one divided ridge, distinctly shows that the species is a 

 Pholadomya. 



In general aspect this and the allied species resemble Cardiinn (just as those 

 of Ceromya are similar to Glossus), but the tliin structm-e of the shell readily 

 shows the distinction, even should it not be possible to examine the hinge. 



Porbes and d'Orbigny both described the Indian form as Cardium, and 

 already identified it wdth the European species. Indeed there is not the slightest 

 distinction between om* shell and that occurring in the upper cretaceous beds near 

 Aachen, in Saxony, and Bohemia. M tiller's statement, that the hinge of 

 the Aachen specimens is perfectly identical with that of a Cardita, is an error. 

 I have examined some specimens obtained through Dr. J. Bosquet and can testify 

 the identity of the hinge with that of Pholadomya. I am not quite certain 



