GASTROPODA. 53 



margin. Tholadomya esmarcU, Nils,, seems also a near relation, but it is easily 

 distinguished froni this species by its straight ventral margin. 



It is easily distinguished from Pholadomya indica by its larger size, more 

 inflated valves and the character of the ribs. 



2. Family : MTIDM. 

 Genus : CORE OLA, BrugiSre. 

 CoEBULA HABPA, d'Archiac and Haime. 



1853. Corbula harpa, d'Archiac and Haime, Descr. des Anim. foss. da Grroape Nnmm. de I'lnde. 

 p. 236, pi. X\I, figs 8, a, 6, 9. 



This species is only represented by a couple of fragments of the right valve and 

 they are too ill preserved to allow a detailed description. It would hardly have been 

 possible to identify them, if better preserved specimens from Sind had not been 

 available for comparison. 



I shall delay a detailed description of this species till I am able to describe the 

 cretaceous fossils from Sind, but it is as well to remark here, that d'Archiac 

 has overlooked a very characteristic feature in the ornamentation of the right valve. 

 He states that it shows nothing but concentric striae of growth. Now, nearly all 

 the specimens from Sind exhibit on the anterior half of the right valve about six 

 fine, but somewhat irregular radiating ribs, which are rather widely distant from each 

 other. Unfortunately these ribs are so delicate that they become effaced if the 

 surface is in the slightest degree weathered, otherwise they form a very distinctive 

 feature of this species. 



Locality and stratigraphical position. — Mazar Drik, horizon 8. 



v.— GASTROPODA. 

 Order : PROSOBRANCHIATA. 



Suborder : ASPIDOBRANCHIATA. 

 Family : TROCHIBJi. 

 Genus : TEOCHUS, Linne. 

 Trochijs laetetianus, Leymerie. PI. XIV. fig. 1-la, 2-2 A. 



1851. Trochus lartetianus, Leymerie, Sur un nouv. type Pyren., M^m. de le Soc. Glol. d« France, 

 2nd Ser., Vol. IV, p. 197, pi. B, fig. 10. 



There are several casts, which, to judge from bits of shelly substance which still 

 adhere, probably represent this species. The turbiform shell consists of low, rounded 



