462 CRETACEOUS PELECYPODA 



numerous closely set ribs, being often interrupted by concentric lamelte of 

 growth, in the narrow ligamental furrow, and in the transversaily subovate and deep 

 muscular scars. 



Locality . — East of Poodoor, in a light brown calcareous sandstone. 



Formation, — Ootatoor group. 



E, costata has been found at a great many localities in the cretaceous beds 

 of North America. Coquand transfers it to the " Campanien," but does not state 

 the reason for this stratigraphical determination. The only European species 

 allied to E, costata is E, Overivegi, Buch; it is a less oblique and more elongated 

 shell. 



6. ExoGYEA Tamulica, Stollczka, PL XLI, Pigs. 2—3 ; PI. XLII, Eig. 1. 



Exog, testa elongato ovata ; valva majors, convexa, inflata, prope umhonem sessili, 

 concentfice confer tim costulata, costiilis undulatis, rugulosis, subnodulosis et suhundu- 

 latis, nonnunquam in parte sub-umbonale striis lamelliformihiis confertissimis stih- 

 stitutis ; timbone valde intorto ; fovea ligamentali longa, marginali, curvata, profunda, 

 angusta, postice latiuscula, infra costa acuta marginata, et infra earn dente transverso, 

 obstuse elongato, instructa ; impressione musculari lata, suh-rotundata, supra, (vel 

 anticej, truncata, sub-centrali ; impress. palliaL dorsaliter, (sen ad marginem con- 

 vexumj, minute crenulata ; fvalvam minor em non vidij. 



A species closely allied to Ex. Fourneti, Coq., (Mon. Ostr. cret., p. 26), but it 

 is more regularly ovate, apparently with the beaks less distinctly incurved, and with 

 the concentric rugulose ribs more distinct. The hinge is decidedly different, there 

 being in the specimens a strongly curved marginal ligamental groove, widening 

 posteriorly, and near the anterior part is a transverse blunt tooth enclosing between 

 it and the beginning of the ligamental furrow a small pit in which evidently a 

 tooth of the other valve fits, quite similar to that in Ex. ostracina ; the muscular 

 scar is subcentric, a little nearer to the beak than to the posterior margin ; it is 

 roundish, with a truncate edge anteriorly, or above. In E. Fourneti the hinge-tooth 

 is represented by a long rib, and the muscular scar is placed more posteriorly, or 

 inferiorly. The upper valVe has not been observed. 



Locality. — Near Arrialoor, in a pinkish calcareous rock. 



Formation. — Arrialoor group. 



7. ExoGYHA SUBORBICULATA, Lamavch, PI. XXXV, Eigs. 1—4. 



1802. GryplicEa suhorUculata, Lamck., Systeme des An. sans, vert., p. 398. 



1813. Grijphites Ratishonensis, Schloth., Tasch., vii, p. 105. 



1819. GryphcBa Columha, Lamck., An. s. vert., vi, p. 198. 



1869. Ostrea JRaUshonensis, Coquand, Mon. Ostr. cret., p. 121, cum syn. 



Ex. testa irregulariter sub-orbiculata, valva majore inflata, Icjevigata, interdum- 

 que irregulariter rugulose striata, in declivitate antica sulco Icevi haud procul ab um- 

 bo ne ad marginem decurrente notata, umbone valde prominente, attenuato et spiraliter 



