TRANSACTIONS OF WAGNER 

 1430 



^^ TERTIARY FAUNA OF FLORIDA 



and deeply incised ; hinge normal ; the anterior cardinal pustular, the interior 

 margins with shallow flutings. Length 47, height 38, diameter 36 mm. 



A remarkably fine species, abundant in the Chipola beds, and not likely to be 

 confounded with any but the following species : 



Venericardia himerta n. sp. 

 Plate 40, Figure 16; Plate 53, Figure 12. 

 Cardita (sp.) Dall, Trans. Wagner Inst. Sci., iii., part v., p. 1196, pi. xl./fig. 16, 1900. 



Oligocene of Oak Grove, Santa Rosa County, Florida ; Burns. 



Shell robust, large, convex, with full, prosogyrate beaks which completely 

 conceal the lunule and are situated at the anterior fourth of the valve ; hinge- 

 line horizontal, the dorsal margin slightly arched over it, the anterior end pro- 

 duced near the hinge-line, rounded, and then curved obliquely towards the 

 lower posterior end of the valve ; posterior end very bluntly rounded, almost 

 at right angles to the hinge-line ; sculpture of about twenty strong, broad, 

 slightly rounded, ilattish ribs, crossed by narrow, sharp, low imbrications with 

 their short slopes on the dorsal side, separated by somewhat narrower chan- 

 nelled interspaces, the whole crossed by rather irregular, coarse, concentric stria- 

 tions ; in the young the ribs are relatively narrower, higher, and more regularly 

 and distantly •imbricate; hinge normal, the hinge-plate narrower than in V. 

 hadra, the inner margins heavily and deeply fluted. Length 53, height 46, 

 diameter 37 mm. 



This fine species externally has a good deal the look of V. hadra, but on 

 looking at the inner face of an adult valve we see that the beaks in the latter 

 are more anterior, the hinge-line broader and more arched, the lunule exposed, 

 and the outline of the disk, omitting the beaks, is nearly a regular oval, while 

 in V. himerta the form is more nearly rounded trigonal, more abrupt behind 

 and more produced just in front of the beaks. The latter species also attains a 

 larger size. 



Section Cyclocardia Conrad. 

 The species of this section, on the whole, occupy in the cooler seas the place 

 taken in warmer waters by the preceding group. It is therefore not surprising 

 to find them abundant in the cool Miocene waters from which the others have 

 vanished. I have a fragment from the Vicksburgian Guallava beds of Costa 

 Rica which ma}' have belonged to a Cyclocardia, but, on the whole, I think it 

 more probable that it belongs to some form of the previous series. 



