OF SOUTHEEN INDIA. 151 



The figure (Jour. Am. Acad. N. Sc, Phil., 2ncl ser., iii, pi. 34, fig. 18,) of the " only" 

 valve has actually very much the form of a Caryatis, and I confess myself unahle 

 to see how the shell can be generically or suh-generically separated from other 

 fossil and recent Caryatis. The species is from cretaceous rocks. 



8^. Caryatis,* Romer, 1862, (olim Fitar, Hom., 1857). Shell cordate or suh- 

 trigonally ovate, usually of moderate thickness and someAvhat inflated, white or 

 yellowish brown colom'ed, concentrically finely striated, palhal sinus always dis- 

 tinct, triangular or obtuse. Venus tumens, Gmelin, is the type of this very well 

 marked form of Cytherea ; its distinction from others is of great importance in 

 fossil conchology, for to it mostly appear to belong the oldest representants of the 

 genus; of recent species Homer describes 60 and adds two doubtful ones; those 

 contamed in Heeve's Monograph of Diane sadly require a revision, 



8/ Dosiniopsis, Conrad, 1861, (Proc. Ac. N. Sc, Phil, 1864, p. 213, and Am. 

 Journ. of Conch., i, 1865, p. 6). Mr. Conrad (in Am. Jour, of Conch., ii, p. 100,) 

 quotes among the typical species of this so-called generic form Venus ptana, Sow., 

 (=snl)-]}lana, d'Orb.,) from the Upper Grecnsand of Blackdown. To judge from 

 this the form of the shell does not in the least differ from typical Cytherea;, and 

 neither does the hinge appear to diff'er. The species also occurs in our South 

 Indian cretaceous deposits, and I have examined the hinge of this one as well as of 

 authentic Blackdown specimens. The only difference I can find is, that the lunular 

 tooth is rather elongated and almost parallel to the margin. But if we compare 

 with this the hinge of other recent species, as, for instance, Cytli. \IIeretrix\ atte- 

 nitata of Dunker, it is evident that no reason exists for a generic or even sub- 

 generic separation. Of course, if Mr, Conrad wishes to make genera and species 

 to suit formations, and these only, he can often detect distinctions where other people 

 are unable to do so. Conrad considers D. lleeJcii, which is a more rounded shell, 

 as the type species ; I do not know it, but at the same time I cannot see in what 

 to place the characters distinctive from Cytherea. 



Sff. Dione, Gray, 1847, (not Megerle v. Muhlfcld, as stated byDeshayes). 

 Shell similar in form to Callista, moderately compressed, always concentrically 

 densely sulcated, and with a more or less distinct ridge running from the beaks in 

 an easy curve to the infero-posterior margin ; this ridge is sometimes provided 'nith 

 spines; pallial sinus moderate, always distinct, usually lingui-form. The type 

 is Cyth. ]^Dione'\ Veneris, Arg., C= Venus Dione, Linne). Romer notices 

 13 species. 



The so-called genus Amyantis, Con,, which has been proposed for Cyth. callosa. 

 Con., does certainly not deserve to bear a special name. The species only differs 

 by having the fulcra thicker thai} most other species, and rugose. The general form 

 and dentition of the hinge is extremely like Cyth. \_CalUsta'] erycina,, (Linn.). 



8/^. Lioconcha, Morch, 1853 (?). Shell roundish, sub-quadrangular or cordately 

 ovate, sometimes cuneiform, more or less inflated, solid, outer surface concentrically 



* la adopting this name I can only repeat what I said regarding Cytherea, p. 149, (footnote), 



