MARINE MOLLUSCA OF THE UNITED STATES. 159 



state of this species, in which the surface is covered with zigzag 

 fulvous or purplish lines. 



Venus preejjarca, 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.-tl. 1834. 

 Oemma Totteni, Stimson, Check Lists. 1860. 

 Tottenia gemma., Perkins, Bost. Proc, 148. 1869. 



Shell minute, nearly orbicuhu-, equilateral, beaks sliglitly ele- 

 vated ; concentrically furrowed ; violet and white ; margin crenulate. 

 Length 3.5 mill. 



NeiD 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. 1853. 

 Shell small, triangular, solid, shining ; beaks nearlj' 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 tlieir 

 bases, the branchial with two rows of cirri, the anal ciliated. 

 Mantle-margins plicato-dentate. 



1. C. ciNGENDA, Dillwyn. Fig. 395. 



iVentis.) Desc. Cat. Shells. 181.5. 

 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, 



