47 Amkrican East Coast Arcas 47 



This belongs with the larger fossil members of the A. (ransversa group and perhaps 

 should be united witli A. plicaiura. 



Dimensions. — Lon. + 12,-21; alt. +4,-18; semidiam. 8 mm. 



Occurrence. — Pliocene of the Croatan beds, near New Berne, North Carolina. — Dall. 

 Pliocene of the Croatan beds, N. C. — C. U. Museum. 



Area campyla Dall 

 Plate XI, Figvires i, 2, 3 



5'f(J///(7?-f<r (Scrt^/mrra) frtw//ij'/(7 Dall, Wagner Free Inst. Sci., Trans., vol. 3, pt, 4, p. 644, pi. 31, 

 figs. 3, 4, pi. 32, fig. 22, 1S9S. 



"Shell of moderate size, solid, rather rude, the posterior end strongly twisted to the 

 right, the beaks low, and the form somewhat compressed; the umbones are verj' slightly 

 bent forward, and are situated at about the anterior third; left valve with about thirty 

 low, flat radial ribs, becoming wider and sparser posteriorly, crossed by rather rude in- 

 cremental lines, but not nodulous or dichotomous, and with subequal, rather shallow 

 channelled interspaces; the right valve is similarly sculptured and somewhat smaller; 

 cardinal area rather long, narrow, with numerous slightly angular, longitudinal grooves; 

 ends of the hinge-line moderately angular, anterior end of shell rounded, posterior pro- 

 duced, base flexuous, inner margins fluted; teeth numerous, small, uninterrupted, nearly 

 vertical, the distal ones larger and tending to break up into granules. Lon. of a large 

 valve 50, alt. 34 mm; of figured specimen, lon. 38, alt. 27, diam. 20 mm. 



"This species is one of the most abundant in the Floridan Pliocene, and is easily dis- 

 tinguished from any other by its compressed appearance and twisted shape. Some of 

 the allied species have a slight flexuosity, but in none is this feature so pronounced as in 

 A. campyla. A variety with thinner shell and narrower and slightly more elevated ribs 

 was at first thought to be distinct, and may be named var. ceretea.'" — Dall, 1898. 



Occurrence. — Pliocene of the Caloosahatchie, Shell Creek, Alligator Creek, and My- 

 akka River, Florida. — Dall. 



Area transversa Say 



Plate XI, Figures 4, 5, 6 



Area transversa Say, Acad. Nat. Sci. Phila., Journ., ist. ser., vol. 2, p. 269, 1822. 



Area transversa Gould, Invert. Mass., p. 96, 1841. 



Area transversa De Kay, Nat. Hist. N. Y., vol. 5, p. 177, pi. 12, fig. 212, 1843. 



Scapharea (Scapharca) transversa Dall, Wagner Free Inst. Sci., Trans., vol. 3. pt. 4, pp. 643-646, 



659, 1898. 

 Not Area transversa Portlock, Rep. Geol. Londonderry, p. 42S, pi. 34, fig. 4, 1S43. 

 Not Cnciiltcea transversa Rogers, Am. Phil. Soc, Trans., vol. 6, p. 373, pi. 29, fig. i, 1839,=/^. (C.) 



Rogersiana Nyst, Tabl. Synopt. Arcac^es, p. 63, 1848, yfrf^? Dall,=/4. Rogersi Heilprin, Acad. 



Nat. Sci. Phila., Proc. for 18S1, p. 449, 18S2. 



"Shell transversely oblong, rhomboidal, with from thirty-two to thirty-five ribs, 

 placed at nearly the length of their own diameters distant from each other; apices sep- 

 arated by a long narrow space, and situate at the termination of the posterior third of 



