232 NEW-YORK FAUNA — MOLLUSCA. 



Genus Lutraria, Lam. Shell equivalvo, inequilateral, transversely oblong or rounded, gaping at 

 the ends. Hinge with one tooth, which is somewhat complicated; or two teeth, of which 

 one is simple, with an adjoining deltoid hollow, which is oblique and prominent within : no 

 lateral teeth ; ligament internal, attached in a pit. 



L. canaliculata. (Say, Ac. So. Vol. 2, p. 311. Conrad, Mar. Conch, pi. 10, fig. 1. Pl. 31, fig. 

 298 of this work.) Transversely oval-orbicular, very thin and fragile, inflated: valves with equal 

 concentric grooves ; posterior margin short, subreniform, compressed ; a marginal longitudinal 

 irregular subimpressed line, bftween which and the edges the grooves become mere wrinkles; 

 posterior slope nearly straight ; gape considerable : anterior margin regularly curved ; within 

 grooved. Color, reddish white. Length, 2*1 ; breadth, 2 '5. Scacoast, Maryland to Florida. 



L. lineata. (Say, Ac. Sc. Vol. 2, p. 310; Conch.pl. 9. L. papi/ratia, Conrad, Conch, pi. 10, 

 fig. 2.) Transversely suboval, thin: posterior gape patulous; anterior linear, and commencing 

 beyond the hinge slope ; valves unequally wrinkled, undulated within: anterior margin glabrous, 

 and with an indented submarginal line corresponding with the exterior carinated one. Color, 

 tinged with ferruginous. Length, 1*9; breadth, 2-7. Georgia and Florida. 



Genus Montacuta, Turton. Shell ovate or oblong, equivalve, inequilateral, nearly closed : hinge 

 with two teeth in each valve, and a cavity between them ; lateral teeth none ; ligament internal. 



M. bidentata. (Montagu, Test. Brit. pi. 26, fig. 5. Gould, 1. c. p. 59.) Shell minute, ovate tri- 

 angular: surface roughened by the lines of growth ; beaks pointed, and near the broader end; 

 tooth on the shorter side oblique and spoon-shaped, for the reception of the ligament. Within 

 faintly marked by radiating lines. Vertical axis, • 1 6 ; transverse ditto, 0*22. Occurs in sand. 

 New-Bedford harbor. Rare. 



Genus Kellea, Turton. Shell somewhat globular, equivalve, closed : hinge with two approximate 

 teeth and a remote lateral tooth in one valve, and a concave tooth and remote lateral tooth in 

 the other ; ligament internal. 

 K. rubra. (Turton, Coneh.Ins.Brit.pl. 11, fig. 7 and 8. Gould, fig. 33.) Shell minute, sub- 

 oval, very inequilateral: beaks prominent, with a smooth elongated and deep area before them* 

 palleal impression distinct, without a sinus. Color: epidermis purplish or soiled brown. Vertical 

 axis, 0' 13; transverse ditto, • 18. Among the roots of seaweed. New-Bedford Harbor. 



