TRANSACTIONS OF WAGNER 

 14^4 



TERTIARY FAUNA OF FLORIDA 



Cape Hatteras, North Carolina, southward to Florida and the Gulf of Mexico, 

 in thirty-six to one hundred and twenty-four fathoms. 



This species grows larger than any of the others and has from twelve to 

 eighteen ribs. The name was first applied to the recent form, which does not 

 appear ever to attain the size and coarseness of sculpture of the fossils, which 

 for this and other reasons were separated by Conrad in 1867 as a distinct species 

 under the name of decemcostata. I cannot satisfy myself that the differences 

 are specific, but if the fossil be considered a variety it may retain Conrad's 

 name, though the number of ribs is not constant. 



Another much smaller Pliocene species was described by Gabb from the 

 clays of Limon, Costa Rica, as Cardita Conradiana. 



Subgenus PTEROMERIS Conrad. 



Venericardia (Pteromeris) acaris n. sp. 

 PLATE 56, FIGURE 4. 



Oligocene of the Bowden marl, Jamaica ; Henderson and Simpson. 



Shell small, plump, inequilateral, the full but rather low beaks situated near 

 the posterior third ; anterior end longer, obliquely produced, rounded, pos- 

 terior dorsal border descending much more steeply, subangular at the lower 

 posterior termination; sculpture of about eighteen broad, flattened radial ribs 

 separated by narrow sulci and crossed by small, arcuate, raised threads, convex 

 dorsally, the ends of these threads projecting sometimes give a punctate effect 

 to the sulci; there is a small, narrow lunule and escutcheon apparently quite 

 smooth ; hinge normal, the laterals distinct ; the inner margins sharply crenu- 

 late, the ligament and resilium wholly external. Length 2.5, height 2.5, diam- 

 eter 2.0 mm. 



This little shell is hardly a typical Pteromeris, but is possessed of all the 

 essential characters and may be regarded as the precursor of the group. The 

 posterior beaks are very characteristic features as well as the distinct laterals. 

 It is the earliest known and smallest of the species. 



Venericardia (Pteromeris) perplana Conrad. 

 Cardita perplana Conrad, Am. Journ. Sci., xli., p. 347, pi. ii., fig. 16, 1841 ; Tuomey and 



Holmes, Pleioc. Fos. S. Car., p. 68, pi. xix., fig. n, 1856; Emmons, Geol. Rep. N. Car., 



p. 302, fig. 235, 1858. 

 Cardita abbreviata Conrad, Am. Journ. Sci., xli., p. 347, pi. ii., fig. 17, 1841 ; Tuomey and 



Holmes, Pleioc. Fos. S. Car., p. 69, pi. xix., fig. 12, 1856. 

 Astarte abbreviata Conrad, Fos. Medial Tert, p. 77, pi. xliii., fig. 12, 1845. 



