220 CRETACEOUS PELECYPODA 



respect Avitli cacli other, and wliatcver slight variations there are to be observed in 

 the coarseness of the concentric or radiating ribs they are common to both. 



Loeal'dies. — Garudamungahim, Serdamungalum, Alundanapooi'am, Anapaudy, 

 &c. ; very common ; either in a bkiisli calcareous sandstone or more frequently 

 occurring in a brownish earthy limestone, sometimes passing iuto a conglome- 

 ratic rock. 



Foi'inaiion. — Trichiuopoly group. 



In Europe the species is found almost everywhere in Ccnomanien, Turonien, 

 and Senonien dejiosits, particularly, however, in the middle series. It is also re- 

 corded by Prof. E. Eomer from Texas, but the figure given of one of the specimens 

 would, I think, indicate a different species with the anterior (especially the lower) 

 edge shorter and the ribs more distant. 



2. Protocardium delicatulum, Stoliczha, PI. XIII, Eig. 8. 



Prot. testa tceniolata, siib-orhmdata, moderate convexa, 2)0stlce sub-tnmcata, 

 nmlonibtis prominentibtis, lateraliter compi'essis ; superjlcie concentrice lente striata, 

 postice radiatim multi-costtdata. 



Height of shell : its length... ... ... ... ... 1'02 



Thickness „ : ... ... (approximately) ... 068 



This species is closely allied to Frot. hillamim, but is decidedly higher, with 

 more prominent umbones, more numerous ribs on the posterior declivity and alto- 

 gether of a thinner structure. 



Localdij. — Shutamungalum, in a light grey sandstone, apparently belonging 

 to the upper sei'ies of the cretaceous deposits. 



Formation. — ? Arrialoor group. 



3. Protocardium PoNDicnERiENSE, d'Orbigmj, PI. XII, Eigs. 1-7. 



1847. CanJinm Ponticerieii.se, d'Orb., Voj-agc Astrolabe, &c., Pala;ont., pi. 5, figs. 21-22. 



Frot. testa sub-trigonata, moderate ivjlata, crassa, paiUo altio'e qnam tonga, 

 suh-cequilaterali, siib-recta ; umbonibus valde prominentibiis, lateraliter contj^ressis, 

 incurvis instrueta, antice ac infra ad marginem lente rotundata, j)ostice oblique trun- 

 cata, vix prodiicta ; snjjerficie cost is concentricis crassis, rotuudatis in declivitate 

 antica scvpissime siib-obsoletis notata ; decVwitate postica costis 20-24 radiantibits paulo 

 prominulis confertim tecta, ad marginem iuteriorem denticulata. Cardu dentibiis 

 ci'assis sicut in speciebus typicis instructus. 



Height of shell : its length ... ... ... ... 1-02 



Thickness „ : „ ... ... ... ... 083 



As to form this species is intermediate between Frot. hillanum and Frot. 

 allnm, being more regularly triangular and less high than the latter; the concentric 



