OF SOUTHERN INDIA. 79 



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

 ^1. Pholadomya caudata, Bomer, PL II, Pigs. 10-11, and PL XVI, Pig. 19. 



1839. Corhula wquivalvis, Goldf., Pet. Grerm., pi. 151, fig. 15 (non Ph. cBqualis, seu cequivalvis, Sowerby, 1823, 



Pusch, &c.). 

 1841. Pholadomya caudata, Eomer, Verst. Norddeutscli. Kreidegeb, pi. 10, fig. 8, non Gon. (or Ph.) caudata 



Ag., 1842). 

 1843. Pholadomya caudata, Romer apud G-einitz, Kieslingswalda, pi. 1, figs. 2S-^0,~idem Reuss. 



1845. Cardium caudatum, Romer^ Bronns' Jabrb. f. M. und GeoL, &c., p. 388. 



1846. PoromyacBquivalvis, Forbes, Trans., Greol. Soc, Lond., 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'Orbigny, Pal. de la voy. d' Astrolabe et Zelee, pi. 4, figs. 25-26. 

 1847. Cardita Goldfussi, Muller, Petref. Aacbner Kreidef., pt. i, p. 20. 



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



1850. „ „ d'Orbigny, Prod, ii, p. 234,— (^iem Ryckholt and others). 

 1865. „ cequivalvis, „ Pict. and Camp., Pal. Suisse, 4°^® ser., 3"ie p^.^ p. 94 

 1867. „ caudata, Rom., Eicbwald, Leth. ross., ll"^e i^yj.^^ p_ 7^9^ 



Fh, testa ovato-oblonga^ tenuis tiimida, suh-irKEquilaterali^ cequivalvi (? )^ postice 

 paiilo longiore, suhcaudata et anguste hiante, umhonihus latis, incurvis instructa in 

 superUcie costuiis tenuibus, cremilatis^ cequalibus^ radiantihus, confertis, in parte 

 postero-siiperiori ohsoletis sed tineis pimcturatis substitutis notata ; cardine in valva 

 sinistra lamina unica brevi, in valva dextra duabiis infra umbonihus sitis fossa 

 mediana separatis instructo ; fulcris ligamenti parvis. 



Height of shell : its length ... ... ... ... 077 



Thickness „ : „ ... ... ... ... 076 



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 incurved. The surface is covered with very numerous, equal, radiating 

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

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

 of this punctured surface that Prof . Porbes thought the species to be a Foromya, 

 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 

 Fholadomya. 



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

 of Ceromya are similar to Glossus), but the thin 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 with the European species. Indeed there is not the slightest 

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

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

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

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

 the identity of the hinge with that of Fholadomya, I am not quite certain 



