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1069 



TERTIARY FAUNA OF FLORIDA 



transverse diameter as compared with its height, its broader and heavier hinge- 

 plate, and its less angular or rather totally rounded anterior end. I give the 

 dimensions for comparison : 



/. humana L. , alt. 70, Ion. 76, diam 



Hoernes's figure, " 70, " 70, " . . . . 



Height from hinge-line to base, /. Iminmia, . . 

 " " " " " Hoernes's figure, 



" " " top of beaks, / huuiajia, 



55.0 mm. 

 71.5 mm. 

 65 mm. 

 60 mm. 

 5 mm. 



" " " " " Hoernes's figure, 10 mm. 



Hoernes states, and his figures support the statement, that the Vienna 

 shell is more ponderous than the recent one, and I may say that the com- 

 parison of a large series of the latter from various localities shows nothing 

 comparable with the characters of the former. I would therefore propose 

 the name of Isocardia Hoernesi for the type from Gainfahren, Vienna Miocene. 



Superfamily CARDIACEA. 



Family CARDIID^. 

 Genus OAHDIUM Linne. 



< Cardium Linne, Syst. Nat., ed. x., p. 678, No. 272, 1758; Mus. Lud. Ulricse, p. 483, 

 1764; Syst. Nat., ed. xii., p. 1121, 1767. First species C. costatum L. 



Cordiformes Da Costa, Elem. Conch., pp. 267-68, 1776; ex. fig'd. C. unedo L. (work 

 not strictly binomial in nomenclature). 



Cardium Muller, Zool. Dan. Prodr., p. 246, 1776; C. echinatum et ednle L. ; Humphrey, 

 Mus. Calonnianum, p. 49, 1797; Bolten, Mus. Boltenianum, ed. i., p. 189, 1798; ed. 

 ii., pp. 132-34, 1819; Bruguiere, Encycl. Meth., i., pp. 203-235, 1789; Lamarck, Pro- 

 drome, p. 86, 1799; sole ex. Cardium aculeatum L. 



The genus Cardium as originally proposed by Linne was nearly homo- 

 geneous. He named no type, and Bruguiere was the first to eliminate Iso- 

 cardia (which he placed with Cardita) , but he also contented himself with 

 saying that the spiny species were originally typical, and named none of them 

 as an exemplar. Hwass (in Humphrey) seems to have followed Bruguiere, 

 and Bolten was the first to make a formal division of the genus. He separated 

 the species into three genera, Corculum, containing shells of the C. cardissa 

 type; Fragum, with the "strawberry heartcockles" like C. unedo; and Car- 

 dium proper, which was also divided into lamellate, costate, imbricate, dentate. 



