37 American East Coast Arcas 37 



with light rusty brown; radiately ribbed, ribs numerous, narrow, about forty in number, 

 most of which are cut or divided by a rather deep groove; area of the ligament elongated, 

 rather wide; umbones full * * *. 



"This shell is probably one of those that have been confounded with the Area anli- 

 quata * * *; it differs in having a much greater number of ribs, and a larger proportion 

 of them more distinctly grooved." — Reeve, 1844. 



Three complete specimens of this rather rare species show thirty-three, thirty-four 

 and thirty-seven ribs. One is stained with reddish brown on the umbo and near the 

 hinge like Reeve's shell, the other two are nearly white like the shell Conrad named 

 Anomalocardia floridana. Shell slightly inequivalve, posterior end produced, somewhat 

 attenuate; teeth small and even; epidermis brown, thick and scaly near the margins. A. 

 sedicostata is verj- similar to its ancestor A. liniosa. The ribs are comparatively narrower, 

 the secondary longitudinal grooves appear only near the umbonal ridge and the beading 

 on the ribs is not so conspicuous. In two specimens the posterior margin is nearly 

 straight in the young part of the shells, but in one the young is auriculate. Recent shells 

 listed as A. lienosa are A. secticostata. 



Dimensions. — Lon. + 26,-58; alt. 4-8,-37; diam. 45 mm. 



Ocairrence. — Pleistocene of North Creek, Little Sarasota Bay, Florida. — Dall. Re- 

 cent from Long Key, Gulf of Mexico; Galveston, Texas. — Conrad. Recent from Porto 

 Rico. — Da/l. Recent from Vera Cruz, Mexico. — Baker. Recent from Tampico, Mexico. 

 — Hinldey. Recent from Florida. — C. U. Museum. Bull. 37, U. S. Nat. Mus., gives the 

 range of -4. lienosa Say, recent, as from Hatteras to Trinidad. This is A. seeticostata. 



Area dodona Dall 

 Plate VIII, Figures 6, 7, 8, 9, 10 



Scapharca (Scapharca) dodona Dall, Wagner Free Inst. Sci., Trans., vol. 3, pt. 4, p. 640, pi. 31, 



fig.s. I, 8, 8a, 1898. 

 Area {Scapharca) dodona Maury, Bull. Am. Pal., vol. 3, p. 375, 1902. 



"Shell small, solid, inequilateral, inflated, and rounded in front, pointed and atten- 

 uated behind; with mesially impressed, prosoccelous beaks; left valve with thirty-six 

 squarish radial ribs, each with a deep central groove longitudinally, the portions on each 

 side with a shallower longitudinal sulcus, so that each rib. except in young shells, is com- 

 posed of four threads set in two pairs; the ribs separated from each other by channelled 

 interspaces about half as wide as the ribs; concentric sculpture of numerous rather close 

 set, regular, blunt, elevated lines, which appear on the riblets as fine undulations; beaks 

 at the anterior third; cardinal area, with a raised margin, lozenge-shaped, rather wide, 

 slightly narrower behind the beaks, with about four rather wavy sets of concentric 

 grooves; hinge-line short, solid, the teeth not interrupted, larger distally, the most an- 

 terior tending to break up into granulations, about fifty in all, subvertical, shorter in the 

 middle of the hinge; margins of the valve deeply fluted; right valve with wider inter- 

 spaces and narrower, often tripartite, ribs. Lon. 40, alt. 28, diam. 30 mm. 



"This fine shell has a neat and elegant surface sculpture, and is one of several which 

 the Oak Grove marl contains and which appear to be new." — Dall, 1898. 



