144 CRETACEOUS LAMELLTBRANCHIA. 



1813. Venus likeolata, /. Sowerby. Miu. Couch., vol. i, p. ^>7, pi. xx (upper 



figure). 

 1828. — — /. Fleming. Hist. Brit. Auimals, p. 449. 



1836. Cypeina rostrata, J. de C. Soiverbij. Trans. Geol. Soc, ser. 2, vol. iv. pp. 



240, 341, pi. xvii, fig. 1. 

 183C. Cytherea lineolata, Snverhy. Iliid., p. 240. 

 1850. Cyprina rostrata, A. cVOrhicjmj. Prodr. do Pal., vol. ii, p. 161. 

 1864. — — J. Morris. Cat. Brit. Foss., ed. 2, p. 199. 



1854. Cytherea lineolata, Mnrris. Il)id., p. 200. 



18C5. Cyprina rostrata, F. J. Picfet aud G. Cainpichc. Foss. Terr. Cn't. Stc. Croix 



(Mater. Pal. Suisse, ser. 

 4), pp. 222, 229. 

 1870. — — F. StoUczha. Paloeont. Indica, Cret. Fauna S. India, 



vol. iii, p. 193 (VenlUcarilla). 

 1907. — lineolata, R. B. Newton. Proc. Malacol. Soc., vol. vii, p. 284, 



pi. xxiv, fig. 14. 



Non 1844. — —A. (VOrligny. Pal. Franc. Terr. Cn't,, vol. iii, p. 98, 



pi. fclxxi (Cyprina neocomiensin. 



d'Orbigny, Ibid., p. 759). 



Measurements .- 



Affinities. — This species differs from G. nnfjnlata in its more prominent and 

 more strongly curved umbones, in tlie shorter posterior margin and tlie greater 

 slope of the postero-dorsal margin, and in the more deeply depressed luniilar 

 region. IMic hinge also differs : in the right valve the median cardinal tooth is 

 tlistinctly separated from the anterior cardinal and is dorsal to the latter and 

 continuous with the posterior cardinal tooth ; the latter is either undivided or the 

 division is indistinctly shown. 



Bemarlcs. — C. linedlatu varies considerably in the prominence and curvature of 

 the umbones, and, as a result, in the outline of the shell. An extreme form was 

 figured by J. de C. Sowerby as the type of ('. rostrata; in specimens in which the 

 umbones are less ))rominent and their anterior curvature less pronounced the out- 

 line of the shell becomes less triangulai-, and in some cases approaches that of G. 

 nngvlata, but the differences in the liinge of the right valve and the greater depth 

 of tlu' hiuular ivgioii appear to l)e present in all specimens. The average size of 

 this species is considerably less than that of ('. (iiujiddta. 



The type of ^^;//^•^■ liiiniltilit, Sowerby (!'. castrensis, Parkinson), from IJlack- 

 down, agrees willi tlic iioi'uial forms of G. riixlr(it<i, except for tlie presence of 



