172 CEETACEOUS PELECYPODA 



areal convex, with the edge bent in, so as to make the ligament less prominent than 

 is often the case in other species. The anterior end is rounded and the posterior 

 somewhat narrowly truncated, the inferior margin being a little flexuous towards 

 the posterior end. Specimens are, however, occasionally met with with a more 

 regularly oval form (see fig. 11). The hinge is similar to that in the species 

 previously noted. The posterior cardinals are in both valves deeply grooved, and 

 the lunular of the left valve is much elongated. The pallial sinus is short, obtuse, 

 and ascending, slightly larger than in Cyth, Botomagensis^ A.' Ovh., to whioh. ouv 

 species also bears some resemblance. The form is entirely that of a Cytherea of 

 the concentrically ribbed or striated type (like Cyth, lirata, Sow.), while the Callistce 

 mostly are flatter, though it is really difficult to fix a proper limit in such 

 cases. 



Localities, — North of Kunanore, north-east of Karapaudy, in a light greyish 

 soft sandstone. 



Formation, — Arrialoor group, . 



\/ 5. Cytheeea [ ? Callista] solitaeia, Stoliczka, PL V, Fig. 20. 



Cyth, testa elongate elUptica^ valde incequilateraliy moderate convexiuscula^ antice 

 hremter et late rotundata, postice sub-truncata ; declivitate lunulare et areale aut 

 convexiusGulis^ aut prima applanata, altera convewa et intus furcata, extus ohtu- 

 siuscula ; margine ventrale fere recto, levissime curvato ; superficie striis subtilissi- 

 mis et nonnullis liris sub-ohsoletis imprimis prope umbonem distinctis notata ; umbone 

 valde incurvo, acuto ; lunula haud distincter marginata, medio elevata, Cardo in 

 valva sinistra dentibus cardinalibus tribus, tenuibus, posiico pe7'longo, duobus alteris 

 multo brevioribus et dente lunulare lamelliforme, fossa profunda ab margine lunulare 

 separato instructus. 



Height of the right valve : its length ... ... ... 0*69 



Thickness (supposed) of both valves : height... ... ... 0*55 



This is a remarkable shell and undoubtedly belongs to the type of Callista^ 

 which is represented among recent shells by Cyth, gigantea, Chem., and of which 

 I have already (p. 150) stated that it may probably form a distinct sub-genus 

 together with a few other known forms. The posterior cardinal tooth is very 

 elongated and the two others are small ; this character greatly resembles Baroda 

 of the TAPusiN^, but the strong lunular tooth is wanting in that sub-family. 

 In our species the lunular tooth of the left valve is strong, lamelliform, and 

 separated by a broad and deep groove from the lunular margin itself. The form 

 of the fossil shell is also peculiarly elongated, like that of Baroda ; the surface 

 is concentrically finely striated, but there are some broadish sulci to be observed 

 near the strongly incurved umbo. 



The fact, that the two sections of Callista are represented in cretaceous rocks, 

 and that the usual lirated species are here already much more numerous than those 



