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613 



TERTIARY FAUNA OK FLORIDA 



Miocene of Wilmington, Cape Fear, and Duplin County, North Caro- 

 lina; Pliocene of the W;iccamaw beds, South Carolina, and of the marls of 

 the Caloosahatchie and Shell Creek, Florida. Recent, in two to one hundred 

 and seventy-five fathoms, from the vicinity of Cape Hatteras, North Carolina, 

 to the West Indies, Nicaragua, and Barbadoes. 



The differences upon which Conrad founded his species aratus are such 

 as may be observed in any large series of the recent pectii/atiis. The ribs 

 vary from twenty to forty in number, very greatly in prominency and adjacency, 

 and the incremental lines from obscure to sublamellose. The truncation varies 

 in amount and sharpness. In a variety carinata, the^ ribs, instead of being 

 rounded, are more or less carinate, like those of acuticostata. All the differ- 

 ences of the fossils can be paralleled in the recent shells. 



G-lycymeris duplinensis n. s. 

 PLATE 34, FIGURES 6, 7. 



Miocene of the Natural Well and Magnolia, Duplin County, North 

 Carolina ; Burns. 



Shell small, rounded-triangular, solid, moderately convex, with pointed, 

 small, low beaks and a flattened lunular area; sculpture of strong, distally 

 bifurcated radial ribs, separated by slightly narrower channelled interspaces ; 

 nine anterior and nine posterior ribs on the lateral slopes are smaller, while 

 on the middle of the shell are about ten larger ribs ; transverse sculpture 

 of regularly spaced, elevated concentric lines overrunning the whole shell ; 

 cardinal area small and short, with -three or four concentric angular grooves; 

 teeth small, vertically striated, six or seven on each side, the line strongly 

 arched and uninterrupted ; anterior margin straight, base rounded, posterior 

 slightly arcuate; basal inner margin with about ten flutings. Largest valve, 

 Ion. 9, alt. 10, diam. 6.5 mm. 



This pretty little species is readily distinguished from any of the varieties 

 of G. pcctinata by its bifurcated and prettily sculptured ribs. It seems to be 

 rather abundant at the locality mentioned. 



Subfamily ARCIN./E. 

 ('onus ARC A (Linne) Lamarck. 

 .\y,-ii (I..) Lamarck, I'rocliomo, p. 87, 1799. Type ./. //<<' T.imic. 



In the selection of the " Noah's Ark Shell" as the type of the restricted 

 genus, Lamarck followed the ancient usage and continuous practice of natur- 



