306 Annals of the South, African Museum. 



Family CARDIID^. 



Genus CAEDIUM, Linnaeus. 

 Cardium denticulatum, Baily. 

 Plate XXXVI., fig. 11. Plate XXXVII., figs. 1-2. 

 1855. Cardium denticulatum, Baily, Q.J.G.S., xi., p. 460, 



pi. xiii., fig. 4. 

 1870. Cardium denticulatum, Stoliczka, Cret. Fauna S. India, 

 p. 214 {Acanthocardium). 

 Non 1871. Cardium denticulatum, Griesbach, Q.J.G.S. xxvii., p. 67, 

 pi. iii., fig. 12. 

 Description. — Shell stout, inflated, oval, higher than long, only 

 slightly inequilateral. Anterior and ventral margins rounded ; 

 posterior margin with a smaller curvature than the anterior. Pos- 

 terior part of the valve sloping more abruptly than the anterior part. 

 Umbones median, prominent, curving strongly inward and slightly 

 forward. 



Ornamentation consists of fi'om 28 to 34 strong, sharp, much 

 elevated ribs with spinose or knotted summits, and separated by 

 deep furrows much broader than the ribs. On the posterior slope 

 of the valves the ribs are less spiny and closer together ; near the 

 anterior margin they are smaller. Fine growth-lines cross the 

 furrows and ribs. Margins of valves toothed ; the tooth-like pro- 

 jections being especially strong on the posterior margin. 

 Length 26 . 24-5 . 16 mm. 



Height 30-5 .28 .21 „ 



Affinities. — C. denticulatum is allied to C. incomptum, Forbes," 

 from the Trichinopoli Group, but the latter has fewer and broader 

 ribs with stronger spines on their summits. 



C. acuticostatum, d'Orbigny,f from the Quinquina Beds, shows 

 some resemblance to C. denticulatum, but its height and length are 

 equal, or almost equal, so that the outline of the valve is more 

 nearly circular than in C. denticulatum ; the ribs are less distinctly 



* Trans. Geol. Soc, ser. 2, vol. vii. (1846), p. 145, pi. xv., fig. 15. Stoliczka, 

 Cret. Fauna S. India, vol. iii. (1870), p. 216, pi. xi., figs. 3-7. 



t Voy. Amerique Mer., vol. iii. (1842), p. 120, pi. xii., figs. 19-22. D'Orbigny, 

 Voy. Pol. Sud. (Atlas, 1847), pi. v., figs. 17-20. Moricke, Neues Jahrb. fiir 

 Min. etc., Beil. Band x. (1895), p. 103. Wilckens, Ibid., Beil. Band xviii. (1904,, 

 p. 231, pi. xix., figs. 7-10. 



