146 AMERICAN MARINE CONCHOLOGY. 



Spurious Species. 



Mactra nucleus, Conrad. This species, described from two odd 

 valves stated to have been collected at Long Branch, N. J., is now- 

 ascertained to be a Manilla species. 



Genus RAETA, Gray. 



1. R. CANALIOULATA, Say. Fig. 343. 



Journ. Philad. Acad., ii. 311. 1822. 



Shell transversely oval orbicular, very thin and fragile, inflated ; 

 valves with equal concentric grooves ; posterior margin short, 

 subreniform, compressed ; a marginal longitudinal irregular sub- 

 impressed line, between which and the edges the grooves become 

 mere wrinkles ; posterior slope nearly straight ; gape considerable ; 

 anterior margin regularly curved ; within grooved. White. 

 Length 2.5, height 2 inches. f 



New Jersey, soutJiwards. 



2. R. LINEATA, Say. Fig. 344. 



Journ. Philad. Acad., ii. 310. 1822. 



Shell transversely sub-oval, thin ; posterior gap patulous ; 

 anterior linear, and commencing beyond the hinge slope ; valves 

 unequally obsoletely wrinkled ; anterior margin smooth with a 

 carinate$ line. White. 



Length 2.75, height 2 inches. 



New Jersey, southwards. 



Family 



Animal with the mantle widely open in front, its margins 

 fringed; foot tongue-shaped, compressed; siphons separate, 

 generally very long and slender; palpi large, triangular; gills 

 united posteriorly, unequal, the outer pair sometimes directed 

 dors ally. 



The shell is free, compressed, usually closed and equivalve; 

 cardinal teeth two at most, laterals 1-1, sometimes obsolete; 

 muscular impressions rounded, polished ; pallial sinus very large ; 

 ligament on the shortest side of 4;he shell. 



The Tellens are found in all seas, chiefly in the littoral and 

 laminarian zones ; they frequent sandy bottoms, or sandy mud, 

 burying beneath the surface. 



