OF SOUTHERN INDIA. 77 



radiating' lines are generally much more easily traceable than on the former. The 

 shell is greatly compressed, the anterior portion being longer than the posterior one, 

 the latter considerably attenuated towards the upper edge ; both ends are roundish, the 

 posterior somewhat obliquely -truncated and slightly gaping. In the middle of the 

 lower edge there is in some specimens a slight indentation observable. The beaks 

 are curved backwards, not very prominent, and in all the specimens which I have 

 examined obliquely fissiu'ed on the posterior side ; this lissm'e has the margins inflect- 

 ed internally, which sometimes appear to unite again ; behind this fissure follows a 

 very long oblique strong rib, which runs along the front edge of the posterior muscu- 

 lar impression and as far below as its base. The hinge is edentulous, but the hinge- 

 margins behind the beaks are internally for some length considerably thickened, and 

 there also are long fulcra externally traceable in each valve. The left valve is 

 usually somewhat larger, and the right one somewhat more tumid, but these 

 characters do not appear constant. 



This is a very charactei'istic species. In size and form it does not resemble 

 any known from cretaceous rocks, but it is rather closely allied to some Jurassic 

 species, such as C. lata or piiiguis. I have great pleasure in associating with this 

 interesting species the name of om* esteemed Superintendent of the Smwey. 



Locality. — In calcareous sandstones north of Akmdauapooram and south- 

 west of Kuuauore ; the species is not uncommon, and the valves are always found 

 closed, indicating that the shells were living at soiue depth in mud in Avhich they 

 w^ere buried, and not on a gravelly groimd and a shallow beach, where shells are 

 sometimes moved about for years and worn off before they become finally imbedded. 



Formation. — Trichinopoly group. 



2. CoiiiMYA PEUTUSA, StoUczka, PL II, Figs. 12-13, and PI. XVI, Fig. 18. 



C. testa elonguta, compressa, pertenui, intiis marffariiacea, in sjipa-Jicie con- 

 ceiitrice striata, ina'qiiilaterali, parte anteriori longiori quam posteriori ; iimboiiihits 

 adpressis, paululum antice versus incur vis ; carditie edeiitulo, intus duabiis costis 

 divergent ibtis instritcto. 



Height of shell : its length ... ... ... ... O'oO 



Thickness „ ; „ ... ... ... ... 019 



Shell much elongated and compressed, very thin, concentrically finely striated, 

 inequilateral, the anterior part about one-foiirth longer than the posterior ; the uj)per 

 and lower margins are sub-parallel, the upper being slightly inclined from the beaks, 

 which are very little prominent, close together, and apparently slightly incm'ved 

 towards the longer end. The internal ribs diverging from the edentulous hinge are 

 very little raised, the posterior is somewhat longer, situated close to the edge of the 

 muscular impression ; the margins of the shell are slightly thickened in front and 

 behind the beaks, posteriorly the short fulcra are distinctly traceable. 



Localitij. — In a calcareous, bluish or bi"ownish sandstone near Pondicherry. 



Formation. — Valudayur group. 



u 



