180 



CEETACEOUS PELECYPODA 



in the middle and gradually sloping towards all the margins, the regular striation 

 intersected by a few deeper sulci are all most characteristic, readily distinguishing 

 it from the last species. The pallial sinus is deep, rather rapidly and obliquely 

 ascending from the infero-posterior end upwards. The hinge is typical of the 

 genus. The right valve has two diverging perfectly divided cardinal teeth; the 

 left two compressed very prominent anterior cardinals and one thin posterior, 

 separated from the former by a broad but along the centre again somewhat raised 

 groove ; this posterior tooth is connected with the broad and thick fulcrum. There 

 is no trace of a lunular tooth, though that portion of the margin is broad, but 

 it is slightly excavated in both valves. 



The common European Cyp, discus, Math., is more compressed, and has the 

 beaks almost always remarkably flattened. 



Localities, — Anapaudy, north of Alundanapooram and Garudamungalum, in 

 a brownish, whitish, or bluish calcareous sandstone ; not rare. 



Formation, — Trichinopoly group. 



y 3. Cypeimeria obesa, d'Orbigny, sp., PL XVII, Pigs. 1-2. 



1847. Lucina ohesa, d'Orbigny, Paleont. Voy. I'Astrolabe, pi. v, figs. 26-28. 



Cyp. testa quadrangulariter rotundata, valde inflata, concentrice striis numerosis 

 siihtilissimis ac siilcis latioribus ad intervalla interpositis notata ; umbonibus obtusius- 

 cutis, paulo prominulis, incurvis ; regione lunulare infra umbones vix excavato, 

 declimtate areale fere rectiuscula, marginibus ceteris uniforme curvatis; area brevi, 

 angustissima ; cardo in valva dextra duobus dentibus divergentibus omnino divisis, 

 postico multo crassiore instructus. 



Specimen figured on pi. xvii, fig. 1. 

 Height : length ... ... 0'88 



Thickness : height ... ... 0*72 



Specimen figured by d'Orbigny, pi. xvii, fig. 2. 

 Height : length ... ... 0-93 



Thickness : height ... ... 0-78 



D'Orbigny gives an enlarged figure of a small specimen, but it evidently 

 represents the same species as the one here described, though the roundness and 

 thickness are slightly larger, which, however, is not unusual in young shells, their 

 convexity generally becoming less prominent as they grow in size. The only 

 right valve which we possess is apparently a little less tumid, because the surface 

 is just in the place of the greatest convexity slightly worn off. The two diverging 

 teeth of the right valve are perfectly divided, and the posterior tooth is thicker 

 than the anterior, which is also somewhat less indistinctly traceable ; the lunula 

 is, as usual in Cyprimeria, not margined, and the area is small and very narrow. 



Locality. — Ninnyoor, in white limestone ; apparently very rare. 



Formation, — Arrialoor group. 



