218 CEETACEOUS PELECYPODA 



s^' 4. Caedium [ACxiNTHOCAEDiUM] PL^LLATUM, StoUczka, PL XI, Pigs. 8-10. 



AcantJi. testa parvula^ rotimdate quadrangulari^ valde inflata^ clausa^ fere 

 (Bquilaterali, antice ad marginem lente curvata^ postice sub-recta; superficie costulis 

 circiter 28-30 radiantibus^ cequidistantibus, acutiusculis, tubercuUs numerosis sub^ 

 spinulosis notatis ornata ; area cardinali moderate curvata, dentibus regularibus 

 instmcta. 



Height of sliell : its length ... ... ... ... 0'92 



Thickness „ : „ ... ... ... ... l-00-0'95 



This species has in general character a much greater resemblance to C. Ottoi^ 

 Geinitz, than the last, but the former has the radiating ribs ornamented with 

 transverse thin lamellae, not with tubercles, as in 0. pullatum, and is also somewhat 

 less inflated than the present species. When the surface of the shell is a little 

 worn off, the ribs appear to be almost smooth (fig. 9), and then the form of the 

 shell becomes more rounded. The hinge^eeth are of moderate size and sharply- 

 pointed. 



Localities. — Neighbourhood of Vylapaudy and Anapaudy, partially in a brown- 

 ish calcareous rock, partially in light coloured sandstone ; rather rare. 



Formation, — Trichinopoly group. 



y 5. Caedium [Cerastodeema] pilatum, Stoliczha, PL XIII, Pigs. 6-7. 



Cerast. testa sub-orbiculata, moderate inflata, incequilaterali, tenui, postice late 

 rotundata; superficie costulis radiantibus numerosissimis^ latiuscuUs, sub-lcemgatis^ 

 interdum squamulose granulatis sulcis angustissimis disjunctis ornata ; lunula Icevi- 

 nsGula, extus hand marginata; car dine dentibus cardinalibus parvis, later alibus 

 lamellosis instructor 



Height of shell : its length ... ... ... ... 0-95 



Thickness „ : „ (approximately) ... ... ... 0'78 



This is the only South Indian species which appears to belong to the sub-genus 

 Cerastoderma, though it is rather too much rounded, but it is distinctly consider- 

 ably shorter anteriorly than posteriorly. The surface is ornamented with very 

 numerous flattened radiating ribs, separated by grooves much narrower than the 

 ribs ; these are in young specimens ornamented with fine lamellar tubercles, which 

 seem to become obsolete with age ; the lunula is smooth. 



Locality, — Ninnyoor, in white soft limestone. 



Formation. — Arrialoor group. 



