422 CRETACEOUS PELECYPODA 



obliquely descending; the ligamental pit lies below the beak, somewhat posteriorly 



from the centre. 



Localities.— ^e^v ComarapoUiam and north of Arrialoor, in coarse silicious 

 sandstone ; near Poodoopolliam, in white earthy limestone. 



Formation.— Ain^oov group. 



There are two species which deserve notice, as being closely allied to the Indian 

 species: E. Bauliniana ^nd ornata oi d'Orbigny; the former is from the Gault, 

 and differs only by a slightly more expanded posterior ear; the other is upper 

 cretaceous, and has the anterior side somewhat more incurved. A comparison of 

 well preserved specimens of these, and one or two closely allied species from 

 the German upper cretaceous beds, would be very desirable, as, for instance, 

 B. asjpera, Mlinst., particularly the form figured by Reus s from Bohemia. 



14. Radula [Acesta] scrobiculata, Stoliczka, PL XXIX, Pig. 6. 



B. [Ac] testa late semi-ovata, ohliqua^ compressiuscula, antice recte suh4runcata, 

 postice rotufidata, auriculis parvis, antica minima^ lunula paulo excavata; superficie 

 striis vel costulis radiantibus, sub-obsoletis, scobinatis^ in parte antica magis distinctiss 

 notata. 



Shell rather broadly semiovate ; valves slightly convex, anteriorly truncate; 

 ears small, the anterior scarcely visible in a side view ; lunula slightly excavated ; 

 surface marked with indistinct radiating scaly ribs, or rather striae, somewhat more 

 distinct on the anterior portion of the shell. Sometimes the scales wear off on the 

 ribs altogether, while the cross lines connecting them, and situated in the furrows 

 between the ribs, partially remain preserved, and this gives the shell quite a dis- 

 tinct appearance from that it originally possessed. The largely ovate, almost 

 semicircular, and rather compressed shape of the valves readily distinguish the 

 present species from any other known from cretaceous rocks ; it in some respect 

 resembles the shape of Flagiostoma. 



Locality, — Near Olapaudy, in a brownish ferruginous rock. 



Formation, — Arrialoor group. 



15. Radtjla [Ctenosteeon] complanata, Stoliczha, PL XXX, Pig. 14. 



B. [Ctenost,] valva sinistra elongata, deplanata, medio costis 10, radiantibus, 

 crassis notata, antice et postice Icevigata ; auriculis magnis, postica minore, antica, 

 majore, ad marginem inferior em ( later alem) simplici, ad anticum (superior em J 

 paulo incrassata et in latere interiore sulco latiusculo instructa. 



Only a single valve of this interesting species was found ; it belongs to the 

 sub-genus Ctenostreon, the larger anterior auricle being internally provided with 

 a shallow but distinct groove for the passage of the byssus ; at the margin itself 

 the groove is indicated by a very slight insinuation (which is scarcely sufficiently 

 indicated in fig. 14, pi. xxx). The left valve is very slightly convex and marked 



