The Venus Clams and Carpet Shells 



used in the Olympian games. The minute umbones top the circle 

 with an acute point. The surface is finely scored with concentric 

 lines. The epidermis is transparent and yellowish on the white 

 valves. Diameter, 3 inches. 



Habitat. — Virginia to West Indies, Texas. 



D. elegans, Conr., has more pronounced and elevated 

 ridges than its near relative. Otherwise they would be confused. 



Habitat. — Cape Hatteras to Texas, West Indies. 



The Heavy Dosinia (D. ponderosa. Gray) is yellowish-brown 

 and smooth outside, except for fine growth lines. The deep lunule 

 is cordate. The valves are white and thick, but the lips are thin 

 as knife blades. Diameter, 4 inches. 



Habitat. — Peru to San Pedro Bay, Cal. 



THE GEM SHELLS 

 Genus GEMMA, Desh. 



Shell minute, rounded or sub-triangular, equilateral; margins 

 crenulated within; hinge short, narrow; muscle scars ventral 

 pallia; sinus vertical. Very small clams abundant on the Atlan- 

 tic coast. 



G. gemma, Totten, about the size of a pea, with elevated 

 beaks, and furrowed, violet-tinged white shell, is a well-known 

 species. A colourless variety with beaks much elevated, abounds 

 from Cape Cod to New York Bay. The gem shell of San Fran- 

 cisco Bay was introduced with seed oysters from Chesapeake 

 Bay. G. purpurea, Lea, is the same species. 



Habitat. — Labrador to Cape Hatteras. 



THE CARPET SHELLS 



Genus TAPES, Muhlf. (PAPHIA, Bolt.) 



Shell transverse, ovate, inequilateral, margins entire; hinge 

 three-toothed; siphons united to middle, divergent, incurrent 

 tube with arborescent tentacular filaments; foot lanceolate, 

 spinning a byssus. 



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