OF SOUTHERN INDIA. 71 



In connection with PJioladomtja 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, elegantulitm, Rdmer, from Texas, one of the species of the same type as 

 PJiol. cmidafa, Goldf., but according to Conrad these shells are said to possess the 

 hinge of Papyrldea (of the Caediidm). Ph. caudata, I satisfied myself, has the 

 hinge of a Pholadomya, but of the other species I liave not examined the hinges. 



39. Cymella, Meek, 1861, (Smith. Misc. Coll., No. 177, p. 31). This has 

 been proposed as a sub-genus for the cretaceous Ph. midata, Meek and Hayden, and 

 characterized as follows : — Shell small, sub-eq.uilateral, and ovate, with niunerous 

 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 Pholadomya, wliich I shall quote as probably belonging to 

 Poromya, answer to this characteristic pretty fairly. 



10, Machoviya, Loriol, 1868, (BuU. Soc. des sc. de I'Yonne, Monog. 6tage 

 Portlandieu, 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 PanopcBce. One Jurassic 

 species {M. Dimkeri, 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 structui-c of the shell the generic determin- 

 ation cannot easily be depended upon. 



When the hinge of 3Iachomya 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 margin. 

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

 Campiche have re-established and placed in the Tellinidm. 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 Anaihia;, and as I have no opportvmity 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 following genera and species have been noticed as oecun-ing- in cretaceous deposits (see 

 Pi etet's Pal. Suisse, iv. ser., 3"'= partie) . Pictet and Campiche admit, of all the A^atiniik^, 

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



Of P.-iiVflOif/iV^ no cretaceous species are as yet known. D'Orbigny transfers Desh ayes' 

 Pandora aguivahis to Crassatella, but the species seems to be much more allied to Fliarclla, or to 

 Psammoljid, than to that genus. 

 TiiHA cnx.K. 



Pictet and Campiche (1. cit., p. IIS,) have referred all the cretaceous species belonging 

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

 one. Tliey do not acknowledge any forms belonging to Periploma or Lj/oiisia. but they point 



