35 Amkkican Kast Coast Akcas 35 



flatter, and obsoletely channelled; near the margin some of the ribs have a second set of 

 finer grooves; hinge-line straight, anterior end descending vertically, then obliquely 

 rounded into the base, which is nearly parallel with the hinge-line; the posterior end de- 

 scends more obliquely and the basal angle is prolonged a little and rounded; the inter- 

 spaces between the ribs in both valves are very narrow, and on the right valve the bead- 

 ing is less conspicuous; the cardinal area is somewhat concave, flattish, with three or 

 four concentric grooves in lozenge form; teeth of the hinge similar, numerous, not inter- 

 rupted, short, vertical, the distal teeth a little longer and more oblique; margin of the 

 valves fluted, the right valve slightly smaller than the other. Lon. 50, alt. 25, diam. 

 20 mm. 



"This species has the appearance of being the Oligocene ancestor of the Miocene A. 

 lienosa, from which it differs by its smaller size, closer and rather narrower ribbing." — 

 Dall, 1898. 



Ribs thirty-five to forty-three, commonly forty or more; sometimes the ribs are as 

 narrow as, or narrower than the interspaces, but not commonly; posterior margin usually 

 serrate. 



Dimensions. — Lon. + 13,-29; alt. +5,-20; diam. 25 mm. This is a rather small 

 specimen. 



Ocmrrcnce. — Oligocene of the Ballast Point silex beds, Tampa Bay, of the lower bed 

 at Alum Bluft", and of the Chipola marl, Chipola River, Florida, — Dall. Oligocene of 

 Bailey's Ferry, Florida. — C. U. Museum. 



Area lienosa Say 



Plate VII, Figures 26, 27, 28; Plate VIII, Figures i, 2 



Area lienosa Say, .-Vm. Conch., 4, pi. 36, fig. 1, 1832. 



Area piotracta Rogers, Am. Phil. Soc, Trans., vol. 5, p. 332, 1837; vol. 6, pi. 26, fig. 5, 1839. 



Area prolrae/a Conrad, Fos. Jlerl. Tert., p. 58, pi. 30, fig. 5, 1845. 



Area protraeta Cvishman, Boston Soc. Nat. Hist., Proc, vol. 33, p. 264, 1907. 



'^o\. Byssoarca prolraela Conrad, Acad. Nat. Sci. Phila., Journ., 2d. ser., vol. i, p. 126, pi. 13, fig. 



36, 1848. 

 Area lienosa Tuouiey and Holmes, Pleioc. f'"os. S. Car., p. 40, pi. 15, figs. 2, 3, 1855. 

 Area lienosa Emmons, Geol. N. Car., p. 284, fig. 204, 1858. 



Seapharea [Area) lienosa Conrad, Acad. Nat. Sci., Phila., Proc. for 1682, p. 579, 1863. 

 Area lienosa Heilprin, Wagner Free Inst. Sci., Trans., vol. i, p. 97. 1887 (ex parte). 

 Seapliara (Seaphara) lienosa Dall, Wagner Free Inst. Sci., Trans., vol. 3, pt. 4, p. 636, 1898. 



"5/^f// rather thin, transversely oblong; ribs about forty, somewhat flattened and 

 much broader than the intervening spaces which are very narrow, and with a longitudi- 

 nal impressed line, particularly on those of the posterior margin, which are almost bifid; 

 and with numerous slightly elevated transvere lines, which being divided by the longitu- 

 dinal striae appear granulated: beak but little prominent, and nearly opposite to the 

 posterior third of the length of the hinge margin: area narrow and elongated : hijige 

 viargin rectiHnear, angulated at each extremity; teeth numerous, small; posterior margin 

 obliquely rounded inwards, no part of it extending further backward than the angle: an- 

 terior margin obliquely truncate: inner margin crcnate." — Say, 1832. 



