378 OEETACEOUS PELEOYPODA 



2. MoDiOLA NITENS5 Forbes, PI. XXXVIII, Eig. 6. 



1846. Mytilus nitens, Forbes, Trans. Geol. Soc, Lond., vii, p. 151, pi. xvi, fig. 8— idem auctorum. 



Mod, testa ovato elongata, tenui ; valvis modice sub-convexis, mitice angustate 

 rotundatis ; postice compressiusculis, sensim dilatatis et ad marginem sub-rotundatis, 

 depressione obliqua paulo profunda ab umbonibus ad marginem antero-ventralem 

 decurrente, umbonibus anticis, latiusculis, depressis, superficie striis incrementi acutis, 

 confertis et tenuibus tecta, 



A small species with a thin shell, elongately ovate, being narrowly rounded 

 in front with almost quite terminal beaks and a shallow rather short depression 

 running from them to the ventral margin ; the posterior part of the shell widens 

 considerably and becomes very flattened towards the rounded margin. The 

 surface shows only fine, sharp concentric striae of growth, but no radiating lines, 

 which are so characteristic for Mod, typica, from which species the present shell 

 also differs by the smaller convexity of its valves. The same difference applies in 

 a comparison of our species with M. Oppeli of Zittel. Eorbes' original figure 

 represents a smaller specimen, but the ventral portion should be a little broader 

 at the anterior end, the species being a Modiola and not a Mytilus, 



Locality, — Olapaudy, in a yellowish earthy rock ; apparently very rare. 



Formation,^ — Arrialoor group. 



3. Modiola polygonAj d'Orbigny, PL XXIII, Eigs. 10-11. 



1846. Mytilus (Modiolus) fulcher, Forbes, Trans. Geol. Soc, Lond, vii, p. 153, pi. xvi, fig. 6, non idem 



Phillips, nee Goldfuss. 



1847. Mytilus poly g onus, d'Orbigny, Voy. Astrolabe Pal., pi. v, figs. 41-42 \—idem auctorum {non pulcherri- 



nus, err ore typico, ind'Orbigny's Prodrome). 



Mod. testa sub-tetragona, regione ab umbonibus ad terminationem postero-inferi- 

 orem diagonaliter extensa rotundate carinata, antice sub-rotundata, postice oblique 

 truncata, margine dorsali brevi, recto, ventrali fere recto, vix insinuato, umbonibus 

 sub-terminalibus, anticis, Icevibus, valde incurvis, approximatis ; superficie striis 

 incrementi tenuibus et alteris radiantibus subtilissimis et confertissimis, vix conspicuis, 

 ornata. 



A very marked, obliquely sub-quadrangular and moderately tumid form, 

 each valve being diagonally provided with a rounded ridge, which more or less 

 projects posteriorly and thus slightly alters the form of the shell. At the margins 

 the valves are peculiarly attenuated, forming sharp edges. Besides the stride of 

 growth which are sharp and very fine, there is almost on the entire surface a very 

 minute radiating striation perceptible under a lens. 



Locality, — Pondicherry, in a light bluish grey sandstone; apparently not 

 common. 



Formation. — Valudayoor group (?). 



