164 CRETACEOUS LAMELLIBRANCHJA. 



Two internal casts from the Cambridge Greensand (derived from the Ganlt) 

 were identified by Mr. Jukes-Browne as Corhis gaultina, Pictet and Roux. The 

 specimens are in the Sedgwick Museum, and no other examples appear to have 

 b een found. The type of C. gaultina came from the Gault of Saxonet. In 

 external form this species agrees closely with Unicardium, but the hinge is 

 unknown, so that the generic position cannot be determined with certainty. 



Unicaedium ringmeriense (Mantell), 1822. Plate XXV, figs. 13, 14. 



1822. Venus? ringmeriensis, G. Mantell. Foss. S. Downs, p. 126, pi. xxv, fig. 5. 

 1850. Panop^a A. d'Orbigny. Prodr. de Pal., vol. ii, p. 157. 



1854. Unicardium ringmeriense, J. Morris. Cat. Brit. Foss., ed. 2, p. 229. 

 1865. Cardium F. J. Pictet and G. Camjnche. Foss. Terr. Cret. 



Ste. Croix (Mate'r. Pal. Suisse, 

 ser. 4), p. 195. 

 Non 1850. Arca ringmerensis, H. B. Geinitz. Das Quadersandst. oder Kreidegeb. in 



Deutschland, p. 162. 

 1872. Mutiella ringmerensis, If. B. Geinitz. Das Elbtlialgeb. in Sachsen (Pal- 



fBontographica, vol. xx, pt. 2), 

 p. 61, pi. xvi, figs. 11-13. 

 1877. A. Fritsch. Stud, im Gtebiete der biJlim. Kreide- 



format. II Weissenberg. u. Malnitz. 

 Schiclit., p. 115, fig. 75. 

 1883. Fritsch. Ibid. Ill Iserschicht., p. 100, fig. 64. 



1889. Fritsch. Ibid. IV Teplitz. Schicht,, p. 78. 



— 1897. Fritsch . Ibid. VI Chlomek. Schicht., p. 54, fig. 59. 



Description. — Shell subquadrate, rounded, inflated, antero-dorsal part com- 

 pressed, length rather greater than height, inequilateral, anterior part larger than 

 the posterior part. Antero-dorsal margin nearly straight. Anterior margin 

 moderately convex, making an obtuse angle with the antero-dorsal margin and 

 curving rapidly near the ventral margin. The latter is moderately convex and 

 curves upward to join the posterior margin, which is slightly curved, and forms 

 an obtuse angle with the postero-dorsal margin. Umbones large, prominent, 

 contiguous, curving forward. Ornamentation consists of strong, narrow, con- 

 centric ridges. 



Measurements : 



(i) (2) 



Length 42 36 mm. 



Height 38 34 „ 



(1) Chalk Marl, Titherlei^h. 



(2) Chalk Marl, Chardstock. 



