374 Viscount d'ARCHiAC and M. de Verneuil's 



We place this very rare shell in the genus Megalodon, not without hesitation. Its external striae and 

 its extremely depressed form would have separated it, if it had not appeared to us that in its hinge it came 

 nearer to this than to any other genus. 



Paffrath ; very rare. 



1. Cypricardia rhomheaf, Phill. Geol. of Yorkshire, Part ii. PI. V. f. 10. 



At Villmar we found an incomplete shell, which appears to be related to Cypricardia rhombea ; but it 

 is more curved, its keel is more elevated, and its beaks are more terminal. 

 Villmar ; very rare. 



2. Cypricardia elongata, nob., Tab. nost., XXXVI. f. 14, 14 a, 145. 



Shell transverse, very much elongated and very inequilateral, inflated in the middle and obliquely 

 truncated posteriorly, where it is prolonged, forming a rounded angle. Beaks very much recurved 

 and advancing forward over the anterior edge. A rounded keel, setting off from the beak, runs to- 

 ward the lower posterior angle. The surface of the valves is covered with very fine, numerous, re- 

 gular and close-set concentric striag, particularly about the beaks and the anterior edge. Length, 8 

 millim. ; width, 21 ; thickness, 11. 

 Although the sections of this shell which we have made have not enabled us to ascertain the details of 

 the hinge with precision, what we have ascertained would not permit us to arrange it with the Megalo- 

 dontes, the cardinal plate being very narrow and the tooth very indistinct. 



The Cypricardia elongata differs from the Isocardia Humboldtii and Sanguinolaria lamellosa (Hce- 

 ninghaus, Goldf., Petref. Tab. CXL. f. 2. p. 207) in being much more elongated, in its beaks being more 

 terminal, and in its more distinct folds being also more regular. Young individuals come nearer in form, 

 being shorter and comparatively wider than in the adult state : but they are less inflated than the I. Hum- 

 boldlii, and their greatest width is in the region of the hinge, instead of being toward the posterior edge. 

 As to the Sanguinolaria undata of Count Miinster (Beitrage, Tab. XII. f. 27.), it might perhaps ap- 

 pear to be still nearer to the C. elongata ; nevertheless, that may be distinguished by the form of the 

 upper edge, which, judging from the figure, is simple and rounded, and would be confounded with the 

 posterior edge, while these two parts form a very distinct angle in tlie Cypricardia elongata. 

 Villmar ; very rare. 



1. Cardium aliforme, Sow., Min. Con. Tab. DLII. f. 2, wax. clathrata, Goldf., Pl.CXLII. f. 1 ^, Tab. 



nost., XXXVI. f. 7, la. 



We have again figured this shell, which is regarded by Goldfuss as a variety of C. aliforme, because 

 the figure given by that author does not express well the two distinguishing characters, and which would 

 have made us regard it as a species, if we had not known intermediate varieties, forming the passage 

 from one to the other. The latter is characterized by two ribs rather stronger than the others, which 

 gives a rectangular limit to the middle and flattened part of the valves. Between these may be seen 

 three, four and even five less distinct, and the whole surface of the shell is covered with fine, close-set, 

 very regular transverse lamellae, which, passing over the small ribs, form a very elegant decussation. 



Paffrath, Eifel. 



2. Cardium palmatum, Goldf. Petrefacta Germaniaj, PL CXLIII. f. 7. Venericardia retroslriata, de Buch. 

 Besides the type of the species figured in the fine work of Goldfuss, we point out the two following 



varieties which ai-e found in the same localities : — 



Var. a. Shell more transverse than the preceding, beaks more recurved, ribs more salient and rounded. 



Var. b. Less inequilateral, ribs flat and narrower than the grooves which separate them. 



These different varieties are very abundant in the ferruginous limestones of Oberscheld. C. palma- 



