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. 



New Jersey, souilnoards. 



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 obsoleteby wrinkled ; anterior margin smooth with a 

 carinated line. White. 



Length 2.75, height 2 inches. 



New Jersey, soutliwards. 



Family TELLINID^E. 



Animal with the mantle widely open in front, its margins 

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

 general^ 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 the 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. 



