TRANSACTIONS OF WAGNER 

 1420 



^ TERTIARY FAUNA OF FLORIDA 



the latter. Lea, however, in 1833 had noticed that the Claibornian form differed 

 at the very least varietally from that of Paris. In 1844 Conrad separated the 

 lower Claibornian from that of the Claiborne sands by the name of densata, in 

 1865 he named a Maryland form variety regia, and about the same time Gabb 

 separated a Californian form under the name of Cardita Horiiii, which had 

 been referred to V. planicosta by Conrad. Paleontologists generally, having 

 regard to the variability of these shells, nevertheless continued to call them 

 V. planicosta, and, lastly, M. Cossmann in the work above cited points out and 

 illustrates anew the distinctions between the form from the Claiborne sands and 

 that of Paris, and would adopt for the American species thus segregated the 

 name of densata, given by Conrad to the dwarfed variety from the lower Clai- 

 bornian or upper horizon of the Lisbon section. 



In England a comparison of specimens by S. V. Wood in 1871 led to the 

 separation from V. planicosta of two varieties, laticardo and angusticardo, and 

 d'Archiac has segregated from the continental form a variety suessoniensis. 



The name of Venericardia planicosta was first applied by Lamarck in his 

 " Systeme des Animaux Sans Vertebres," 1801, with the diagnosis " Testa 

 crassissima, costis planis," and a reference to Knorr, " Recueil des monumens 

 . . . petrif.," etc., part ii., pi. xxiii., fig. 5, 1767. He states that it is a fossil of 

 the environs of Paris, also found in Piedmont and near Florence. Knorr's shell 

 is stated to be an Austrian fossil, and is undoubtedly a Cardita, senso lato, but 

 not identical with the French fossil. So it is evident that Lamarck at first 

 confused several species together in his notion of V. planicosta, and the latter 

 in its modern sense will date from his full description and figure in the " An- 

 nales du Museum" of 1807. Curiously enough, Lamarck's figure is closer to 

 the American type than to the average Parisian shell, though the wider nymph 

 and projecting anterior shoulder indicate its origin. 



Sir Charles Lyell, after comparing a Virginian specimen from Coggins 

 Point, on the James River, said it could not be distinguished from one of the 

 common varieties of the European shell. Conrad in speaking of the Maryland 

 shell says it has twenty-two ribs, but either he did not count the smaller ribs 

 on the dorsal slopes or the figures are a misprint for thirty-two, for twenty- 

 two can be counted on his figure, in which the slopes are invisible. Rogers 

 mentions that specimens indistinguishable from the Parisian shell occur in 

 Virginia, but not usually in the same bed with the form which he named V. 

 ascia. 



Most of the paleontologists who have treated of the American shell have 

 regarded it as identical with the Parisian form, but this may be due to the less 



