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TERTIARY FAUNA OF FLORIDA 



This well-marked species is abundant in the shales, but the matrix is so 

 much tougher than the remains of the shell that the characters have to be 

 determined from a large, number of imperfect specimens. 



Cardium (Fragum) sp. indet. 



Oligocene marl of Bowden, Jamaica ; Henderson and Simpson. 



A fragment of a Cardiiuii resembling C. medium was obtained from the 

 marl but is too imperfect for description and is noted here to avoid the omis- 

 sion of this element in the Bowden fauna. It may be the same as the follow- 

 ing species, but is very much larger than any of the Chipola specimens. 



Cardium (Fragum) Burnsii n. sp. 

 Plate 48, Figure 15. 



Oligocene of the Chipola River, Calhoun County, Florida ; Burns. 



Shell small, subquadrate, moderately inflated, truncate behind, rounded in 

 front, with rather low beaks ; sculpture of on the body twenty-two to twenty- 

 four subequal rounded ribs with narrower channelled interspaces, sharply 

 cross-striated between the ribs ; on the posterior truncation twelve to fourteen 

 similar but smaller ribs, a few near the hinge-margin wider than the rest, 

 with no marked smooth area between them and the margin either in front 

 of or behind the umbones ; an easily detachable outer layer covers the ribs 

 with fine concentric threading, rising at intervals into semilunar small nodules, 

 all of which is frequently worn off when the ribs appear polished ; internally, 

 the margin is strongly fluted ; hinge normal, strong. Lon. 6.5, alt. 7.0, diam. 

 6.0 mm. A single broken valve reaches 10 mm. in height. 



This little shell stands almost midway between typical Fragum and Tri- 

 goniocardia, having the striated interspaces of the latter and the numerous 

 similar subequal ribs of the former. It seems abundant in the marls. 



Cardium (Frag-um) medium Linn(§. 

 Cardium medium Linne, Syst. Nat., ed. x., p. 678, 1758; ed. xii., p. 1122, 1768; Reeve, 



Conch. Icon., ii., Cardium., pi, vi., fig. 30, 1844; Roemer, Conch. Cab. Neue Ausg., 



p. 102, pi. iv., figs. 5-7, 1869. 

 Cardium venustum Dunker, Mai. Blatt., viii., p. 27, 1861. 

 Hemicardium columba Heilprin, Trans. Wagner Inst., i., p. 93. pl- xi., fig. 26, 1886. 



Miocene of St. Mary's River, Maryland, W. B. Clark; of the Natural 

 Well, Duplin County, North Carolina ; Pliocene of the Caloosahatchie River, 



