TRANSACTIONS OF WAGNER 

 1428 



TERTIARY FAUNA OF FLORIDA 



especially in the young ; lunule small and impressed ; the beaks are lower and 

 the whole form less oblique than in V '. tetrica; hinge normal, more delicate 

 than in the other species mentioned. Length of a moderate-sized specimen 

 17.0, height 16.5, diameter n.o mm. 



While the spinosity of the posterior ribs is frequently worn away in adult 

 individuals it is quite noticeable in the younger perfect ones, and the relative 

 sparseness of the ribs with their wide interspaces immediately distinguishes it 

 from V. tetrica and other near allies. It reaches, judging by fragments, a 

 length of twenty or twenty-two millimetres when fully grown. 



Venericardia vicksburgiana n. sp. 

 PLATE 56, FIGURE 6. 



Vicksburgian, partly silicified, limestone at Martin Station, near Ocala, 

 Marion County, Florida ; Willcox. 



Shell small, squarish, with small, high, very anterior beaks and about 

 twenty-two to twenty-three rounded, subnodulous, radial ribs, separated by 

 nearly equal, roundly excavated interspaces ; the ribs are lower and thicker 

 than in the species above described and the nodules rounded ; lunule small and 

 impressed; margin with moderately impressed fluting. Length 15.5, height 

 15.0, diameter 10.0 mm. 



Until this was discovered, in the form of silicious pseudomorphs, no Veneri- 

 cardia of this type was known from the Vicksburgian. As the last of its race 

 it is small and degenerate with the feebleness of the sculpture as an indication 

 of senility. 



Venericardia scabricostata Guppy. 



Cardita scabricostata Guppy, Quart. Journ. Geol. Soc. London, xxii., p. 293, pi. xviii., fig. 

 10, 1866; Gabb, Geol. St. Domingo, p. 252, 1873. 



Lower Oligocene of the Bowden beds, Jamaica, and of St. Domingo ; Ven- 

 dryes and Gabb. 



This species is small and has about eighteen ribs. Another more elongate 

 species, perhaps a Cardita, occurs in the Oligocene horizon of the island of 

 Antigua, but my example of it is but poorly preserved. 



Venericardia serricosta Heilprin. 

 PLATE 38, FIGURE 9. 



Cardita (Carditamera) serricosta Heilprin, Trans. Wagner Inst., i., p. 117, pi. xvi., fig. 64, 



1887. 

 Cardita serricosta Dall, Trans. Wagner Inst., iii., part v., p. 1194, pi. xxxviii., fig. 9, 1900. 



