OP 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 obseryable. The beaks 

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

 examined obliquely fissured on the posterior side ; this fissm^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 characteristic 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 pmguis. I have great pleasure in associating with this 

 interesting species the name of our esteemed Superintendent of the Survey. 



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

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

 closed, indicating that the shells were living at some depth in mud in which they 

 were buried, and not on a gravelly ground and a shallow beach, where shells are 

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



Foi^m a tion . — Trichinopoly group . 



y 2. CouiMYA PEUTUSA, StoUczJm, PL II, Pigs. 12-13, and PL XVI, Pig. 18. 



C. testa elongata, compressa, pertenui, intus margariiacea, in superficie con- 

 centrice striata, in(Eqtiilaterali, parte anteriori longiori quam posteriori ; wnbonibus 

 adpressis, paululum antice versus incurvis ; cardine edentulo, intus duabus costis 

 diver gentibus instruct 0. 



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



Thickness „ : „ .•• ••• •■• ••• 0'19 



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

 inequilateral, the anterior part about one-fourth longer than the posterior ; the upper 

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

 which are very little prominent, close together, and apparently slightly incurved 

 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. 



Locality. — In a calcareous, bluish or brownish sandstone near Pondicherry. 



Formation. — Valudayur group. 



u 



