CORBULA. 211 



1865. Isocardia ? angulata, F. J. Pictet and G. Campiche. Foss. Terr. Cret. Ste. 



Croix (Mater. Pal. Suisse, 

 ser. 4), p. 240. 

 1871. Isocardia angulata, F. Stoliczha. Palseont. Indica, Cret. Fauna S. India, 



vol. iii, p. 194. 

 1877. Isocardia? angulata, G. Bohm. Zeitschr. d. deutsch. geol. Cesellsch., 



vol. xxix, p. 241. 

 1889. Isocardia angulata, G. W. La/mplugh. Quart. Journ. Geol. Soc, vol. xlv, 



p. 616. 

 1900. A. Wollemann. Die Biv. u. Gastrop. d. deutsch. u. 



holliind. Neocoms (Abhandl. d. k. 

 preussiscli. geol. Land., N. F., pt. 

 31), p. 114. 



1905. Corbula (Isocardia) angulata, E. Harbort. Fauna d. Schaumberg-Lippe- 



sclien Kreidemulde (Ibid., 

 pt. 45), p. 81. 



1906. Isocardia angulata, A. Wollemann. Die Biv. u. Gastrop. nord-deutsch. 



Gaults (Jalirb. d. k. preussiscli. 

 geol. Land., fur 1906, vol. xxvii), 

 p. 277. 



Description. — Shell with sub-quadrate outline, rounded, occasionally sub- 

 triangular, very convex, equivalve, more or less considerably inequilateral ; length 

 greater than height. Anterior part produced, rounded ; ventral margin slightly 

 curved ; posterior margin truncate, slightly convex, somewhat oblique, forming 

 angles with the ventral and dorsal margins. Postero-dorsal margin sloping 

 ventrally. Umbones moderately large, curved inward and more or less considerably 

 forward, with a carina extending to the postero-ventral angle, cutting off a large, 

 flattened postero-dorsal area. The part of the valve in front of the carina is 

 regularly convex. Lunular region depressed. 



Ornamentation consists of fine concentric striae. 



Measurements : 



(3) (4) 



G-2 . 6 

 5-0 . 5 



(1—7) Speeton. 



Affinities. — This species shows some resemblance to G. gaultina (see p. 214), but 

 is more nearly quadrate in outline, relatively longer, of larger size, and without 

 distinct ribs. 



G. angulata, is fairly common in the Speeton Clay, but no specimen showing the 

 hinge appears to have been found, so that the generic position assigned to this 

 species by Phillips was presumably based on the external character of the shell. 

 Pictet and Campiche thought that it probably belonged to Gyprina. Wollemann 

 states that it is most likely a Corbula, and Harbort, who has seen the hinge, 





(i) 



(2) 



Length 



, 7-1 . 



6-8 



Height 



. 6-0 



. 5-5 



(5) 



(0) 



(7) 



G-o , 



, 5-0 , 



4*5 mm 



4'5 



. 4-1 



• 4-0 „ 



