80 CRETACEOUS PELECYPODA 



whether the shell is perfectly equivalve, for in many instances I found the beaks 

 of the valves somewhat shifted ; tliis is so general that it Avould rather seem natui-al 

 than accidental. The convexity of both valves is perfectly the same. 



Locality. — In bluish and light brown sandstone near Parchaiiy, Serdamunga- 

 lum, &c. 



Formation. — Trichinopoly group. 



In Europe the species has been observed in the upper cretaceous strata of 

 the whole of Germany, in Russia, &c. I am by no means certain whether 

 d'Orbigny's Ph. ( Carditivi) Siihdin'mense is really a different species. 



2. Pholadomya connectans, Forbes, PI. XVI, Fig. 29. 



1846. Ph. ill.. — Trans., Geol. Soc, London, vii, p. ItO, pi. 17, fii;. 5 — idem auctdriini. 



Ph. testa ocato-elongata, inceqiiilaterall, antice breviorl et rolundata, jwstice 

 longiori ac sub-caiidata, j'^fulnlnm auffustiori, fere clausa ; timbonibus prominulis, 

 antice versus incur vis, tat is, approximatis ; siiperjicie concentrice striato-sulcata , ac 

 decern costnlis radiantibus 2^ostice evanidis notata ; margine inferiori timbonibus 

 op)posito sensim injlexo. 



Height of shell : its length ... ... ... ... Oo2 



Thiekne.ss „ : „ ... ... ... ... 043 



This species differs from the next by a smaller number of radiating ribs, more 

 In'oadly rounded anterior end and the indentation of the margin opposite the beaks ; 

 to this indentation extends from the beaks a groove, which is broad, shallow, and 

 rather more conspicuous than other su.lci separating the ribs. In front of the median 

 groove there are three and behind it seven radiating ribs, but on one of the two 

 valves there seems to be another small additional rib traceable on either side. 



Locality. — Poudicherry. I have seen but Porbes' original specimen, of which 

 I give a figure ; the one supplied by Porbes representing this shell is a little shorter 

 than it ought to be. 



Formation. — Valudayur group. 



3. Pholadomya radiatula, Stoliczka, PI. Ill, Fig. 5. 



Pit. testa elongata, inccqitiralvi, antice ac p)Osfice rotundata ; margine supcriori 

 et inferiori subparallelis, timbonibus mediocriter i^rominentibus, incurris, approxi- ^ 

 matis ; superjicie striis incrementi, confertissimis ac costidis tenuibus radiantibus 

 numerosis in parte posteriori obsoletis ornata ; terminatione anterior i angustatim- 

 posteriori distincte, sed non precipue late, hiante. 



Height of shell : its length ... ... ... ... Ool 



Thickness „ : „ ... ... ... ... 0-39 



In the large number of thin radiating ribs this species approaches the lower 

 cretaceous Ph. elongata, but is considerably higher in proportion to its length ; this 



