OF SOUTHEEN INDIA. 71 



In connection with Fholadomya I have to notice Liopistha, Meek (Check 

 List North- Am. Inv. fossils, Cret., Smith. Misc. Coll., No. 177, p. 32). It is based 

 upon Card, elegantulum, Romer, from Texas, one of the species of the same type as 

 PhoL caudata, Goldf., but according to Conrad these shells are said to possess the 

 hinge of Fapyridea (of the Cardiium), Fh. caudata, I satisfied myself, has the 

 hinge of a Fholadomya, but of the other species I have not examined the hinges. 



39. Cymella, Meek, 1864, (Smith. Misc. Coll., No. 177, p. 34). This has 

 been proposed as a sub-genus for the cretaceous PA. undata, Meek and Hay den, and 

 characterized as follows : — Shell small, sub-equilateral, and ovate, with numerous 

 well defined concentric undulations, crossed on the middle of the valves by a few 

 impressed lines, not marked in the depression between the ridges. A large num- 

 ber of those species of Fholadomya, which I shall quote as probably belonging to 

 Poromya, answer to this characteristic pretty fairly. 



40. Machomya, Loriol, 1868, (Bull. Soc. des sc. de I'Yonne, Monog. etage 

 Portlandien, p. 81, pi: vi, figs. 8-9). Shell oblong, sub-compressed, equivalve, 

 strongly inequilateral, rather solid and with punctated surface ; a strong radiat- 

 ing rib issues from the umbones and runs towards the anterior margin ; ligament 

 external, solid. The hinge is not known, but the form of the shell with its 

 strong external ligament appears to form a passage to the Fanopcsce. One Jurassic 

 species (Jf. Dunkeri, d'Orb.,) has as yet been referred to the genus, but many 

 more no doubt exist ; only the principal character of the genus is such that 

 without the examination of the internal structure of the shell the generic determin- 

 ation cannot easily be depended upon. 



When the hinge of Machomya has been made fully known, it will be necessary 

 to compare it with that of Vanganella (of the lutrariin^), which also has an 

 internal anterior rib extending from the umbones towards the anterior maro'in. 

 Equally necessary will be a comparison with Mactromya, which Pictet and 

 Campiche have re-established and placed in the Tellinidje. I have little doubt 

 that Mactromya in part is identical with Machomya ; it has a perfectly similar 

 anterior rib and an external ligament, but as the shell of the latter has the sculpture 

 of that of other Anatincs, and as I have no opportunity to examine the type species, 

 I must leave the question to be settled by those who have better means of obtaining 

 access to the originals. 



List of cretaceous species. 



The folio wiug" genera and species have heen noticed as occurring' in cretaceous deposits (see 

 Pic tet's Pal. Suisse, iv. ser., 3^« partie). Pictet and Campiche admit, of all the Anatinid^, 

 only three genera in cretaceous rocks, Anatina, Thracia, and Fholadomya. 



Of PANDORIN^, no cretaceous species are as yet known. D'Orbigny transfers Deshayes' 

 Pandora aquivalvis to Crassatella, but the species seems to be much more allied to Pliarella, or to 

 P^ammohia, than to that genus. 



THRACIIN^. 



Pictet and Campiche (L cit., p. 118,) have referred all the cretaceous species belonging 

 to this sub-family to Thracia, evidently because they consider this course to be a convenient 

 one. They do not acknowledge any forms belonging to Periploma or Li/onsia, but they point 



! / ^ ^ . , ■V. 



