GYPRINA. 145 



numerous W-sliaped markings on the surface. These appear to be due to the 

 structure of the shell (possibly connected with colour markings), since they are 

 seen only in specimens which are somewhat decorticated, and are in some cases 

 present on one valve but not on the other, or are seen on the dorsal but not on 

 the ventral part of a valve. 



Stoliczka 1 thought that Venus lineolata was probably identical with Cytherea 

 plana, Sowerby, but the hinge and pallial line of the former prove conclusively 

 that it belongs to the genus Gyprina. 



Types. — From Blackdown ; Venus lineolata in the British Museum; 0. rostrata 

 in the Bristol Museum. 



Distribution. — Upper Greensand (zone of SchlambacMa rostrata) of Blackdown. 



Cyprina (Venilioardia) truncata (Sower&y), 1836. Plate XXIII, fig. 3. 



1836. Venus ? truncata, /. de C. Sowerby. Trans. Geol. Soc, ser. 2, vol. iv. 



pp. 242, 341, pi. xvii, fig. 3. 

 1850. subtruncata, A. d'Orbigny. Prodr. de Pal., vol. ii, p. 150. 



1854. Cytherea truncata, J. Morris. Cat. Brit. Foss., ed. 2, p. 201. 

 18G5. Venus subtruncata, F. J. Pictet and G. Campiche. Foss. Terr. Cret. Ste. 



Croix (Mater. Pal. Suisse, ser. 4), p. 190. 

 1870 F. Stoliczka. Pakeont. Indica, Cret. Fauna S. India, 



vol. iii, p. 161 (Caryatis). 



Affinities. — G. truncata is closely allied to, and probably only a variety of 

 0. angulata. The shell is thinner, the posterior margin higher, and the anterior 

 part more produced than in G. angulata. 



This species, or variety, has hitherto been referred to Venus or Gytherea, but 

 a specimen showing the hinge and pallial line proves that it is a Gyprina. The 

 hinge agrees with that of G. angulata. 



An example collected by the late Rev. W. Downes (Plate XXIII, fig. 4) is 

 more elongated and more inflated than the type of G. truncata, but agrees in other 

 respects, and is probably only an individual variation. 



Type. — From Blackdown ; in the Bristol Museum. 



Distribution. — Upper Greensand (zone of Schloenbachia rostrata) of Blackdown. 



Cypkina ligepjensls, d'Orbigny, 1844. 



Internal casts of a large Gyprina have been found in the Cenomanian 

 Sandstone of Wilmington, 2 Devon, and in the cherty blocks in the Eocene Gravel 



1 ' Cret. Fauna S. India,' vol. iii (1870), pp. 160, 169. 



2 Jukes-Browne, 'Cret. Rocks of Britain,' vol. ii (1903), p. 129. 



