MARINE MOLLUSCA OF THE UNITED STATES. 159 
state of this species, in which the surface is covered with zigzag 
fulvous or purplish lines. 
Venus preparca, Say, has not been positively identified ; it may 
be the young either of this or the preceding species. 
Genus GEMMA, Deshayes. 
Tottenia, Perkins. Bost. Proc., 148. 1869. 
1. G. Gemma, Totten. Fig. 393. 
( Venus.) Silliman’s Journal, xxvi. 367, f. 2, a.-d. 18384. 
Gemma Totteni, Stimson, Check Lists. 1860. 
Tottenia gemma, Perkins, Bost. Proc., 148. 1869. 
Shell minute, nearly orbicular, equilateral, beaks slightly ele- 
vated; concentrically furrowed ; violet and white ; margin crenulate. 
Length 3.5 mill. 
New England to North Carolina. 
This species is viviparous, producing three dozen young at a 
time. 
2. G. MANHATTENSIS, Prime. Fig. 394. 
Ann. New York Lyceum, vii. 482. 1852. 
Shell small, triangular, solid, shining ; beaks nearly central, ele- 
vated; surface grooved with remote concentric furrows, inner 
margin crenulated. 
Length and height 3 mill. 
New York. 
It is rather smaller, more triangular, and more deeply and 
regularly grooved than G. gemma, and destitute of purple within 
and without. 
Genus CHIONE, Muhlfeldt. 
Gray, Zool. Proc., 183. 1847. 
The animal has short, broad, unequal siphons, united at their 
bases, the branchial with two rows of cirri, the anal ciliated. 
Mantle-margins plicato-dentate. 
1. C. cineenpDaéA, Dillwyn. Fig. 395. 
(Venus.) Desc. Cat. Shells. 1815. 
Venus cancellata, Lamarck,.Anim. s. Vert. 1818. 
Venus elevata, Say, Journ. Philad. Acad., ii. 272. 1822. 
Shell subcordate, longitudinally sulcated, sulci equal, numerous, 
dense, on the anterior submargin sparse, crossed by concentric, 
