FAMILY PECTINIDJE — PECTEN. 175 



Genus Lima, Brug. Animal with numerous tentacular filaments in many scries along the edges of its 

 mantle : foot very small, and carrying a byssus ; mouth surrounded by a very thick and 

 fringed labial appendage. Shell longitudinal, subequivalve, eared, slightly gaping on one side 

 between the valves : beaks distant ; internal face inclined outwards. Hinge toothless: pit partly 

 exterior, receiving the ligament ; muscular impression central and trifid. 

 L. squamosa, Lam. (Conrad, Mar. Conch, pi. 3, fig. 2.) Shell oblong, with broad and strong scaly 

 ribs: hinge oblique; margin plicate. Color, whitish or yellowish. Length, 1-0 -2*6 j width, 

 0'8-l-2. Florida. 

 L. glacialis, Lam. (Conrad, lb. pi. 3, fig. 1. Pl. 11, fig. 208 of these pages.) Shell oval, sub- 

 equilateral, with numerous subscabrous stria? : margin entire. Color, soiled whitish or dull reddish. 

 Length, 2*5; width, 1-5. Florida. 



FAMIL Y A VICVLIDJE. 



Animal with the mantle entirely open except along the back, without tubes or peculiar openings, and 

 prolonged sometimes behind : foot moderate, with a byssus. Shell often foliated, generally thin, 

 pearly subequivalve. Hinge without teeth, or only showing small rudimentary teeth ; an anterior 

 notch for the passage of the byssus. 



Genus Avicula, Brug. Shell oval, fragile, rather smooth: base transverse, straight ; extremities pro- 

 duced. Hinge linear, unidentate between the beaks : area of the ligament marginal, narrow, 

 channelled. 

 A. atlantica, Lam. (A. hirundo, Say, Ac. Sc. Vol. 2, p. 262.) Shell with numerous undulated 

 wrinkles disposed in rays : wings broad, rounded, scarcely oblique ; valves unequal. Color, red- 

 dish brown. Width, 0-7. Southern Coast. 



