188 CRETACEOUS J.AMEEI.lJUtANCll I A. 



Nou 1803. Venus kaba, H. Dreschtr. Ibid., vol. xv, p. 3-13. 



— 1884. CrrKiMEKiA faba, E. HohaiiJ'd. Ibid., vol. xxxvi, p. 4t)7, pi. vii, fig. 1. 



— 1889. Tapes faba, E. B.ohai>fel. Die MoUusk. Aaclieu. Kreide (Palseonlo- 



i,'r;ipliicii, vol. xxxv), p. 1G5, pi. xiii, figs. 7-lU. 



— 1897. Venus (Tapesj faba, A. Fritsch. Stud, iiii Gubiete dor boLm. Kreide- 



forinat., vi, Clilomek. Schiclit , p. G3, 

 fig. 80. 



— 1901. — — — F. StufiH. Jalirb. d. k. preussisch. geol. Laudesuust. 



fiir 1900, vol. xxi, p. 82. 



Descriptum . — Shell oval, of moderate ctjiivexity, witli flattened sides, con- 

 sidei'ably iiK'{|uilateral. Antero-dursal margin short, slightly concave. Anterior 

 margin rminded, passing gradually into tlic sliglitly convex ventral margin. 

 Postero-dorsal margin long, slight!}' convex, with a moderate or cousidei'able 

 ventral slope. Porterior margin short, rounded or suhtruncate. Umbones small. 

 Lunule elongate, not impressed, faintly limited. Ormimentation consists of small, 

 regular, concentric ribs. 



Hinge: In the right valve the anterior and median cartlinals are stout, diverge 

 slightly, and are directed forwards, and reach the lower margin of the hinge- 

 plate; the two posterior teeth (wliicli represent the posterior cardinal) are 

 laminar, oblique and diverging. In the left valve the anterior and median 

 cardinals are rather stout and divei'ge; the posterior cardinal is slender and 

 obliijue. In front of the antei'ior cardinal there is a concave space on the hinge- 

 plate in hoth valves. 



Inferieure, is somewhat simihii' in form to ('. {Cijrlorisina) j'nlxi, but the surface 

 oF the shell is smooth. 



A species found in tlie Aachen Greensand has been identified by Goldfuss, 

 Holzapfel, and others with Sowerby's I'eiuis faha, but was regarded as distinct by 

 (r()rl)igny ami G. Miillei'. It differs from Sowerby's species in the greater 

 cui'vature of the ventral margin and the moiv pointed posterior extremity ; also the 

 posterior teeth in the right valve are less widely separated and are more oblique. 



In d'Orbigny's figure of Venus faba the ornamentation is coarser than in English 

 examples, but a s[)ecimen from the Cenomanian of Rouen (one of the localities 

 cited by d'Orbigny) differs but little in this respect from Blackdown specimens. 



Remarks. — The principal variation consists in the amount of the ventral slope 

 1 i'al. I'lauv- Terr. Crtt.,' vol. iii (1845), p. 449, pi. ccclxxxvi, figs. t>, 7. 



