238 NEW-YORK FAUNA — MOLLUSCA. 
the posterior placed near to the primary tooth, and shorter than the anterior one. Color, solid 
white. Length, 1-1; breadth, 1+1. Allied to the succeeding species. Georgia. 
A. radiata. (Say, Ib. Vol. 5, p. 220.) Transyersely oval-orbicular, a little compressed. Apex 
nearly central, a little prominent; posterior slope a little concave. Primary teeth two in each 
valve; lateral teeth very distinct. Color, with rosaceous radii, sometimes obsolete ; within tinged 
with yellow, and the rosaceous radii very distinct. Length, 0+9; breadth, 1+1. East-Florida. 
A. lepida. (Ip. Ib. Vol. 5, p. 221.) Shell very much compressed, subtriangular, very thin, pellucid, 
equilateral, with concentric wrinkles and longitudinal stri, which curve on the anterior margin 
towards the anterior edge, and behind towards the posterior slope. Cardinal teeth obsolete; lateral 
teeth prominent. Color, pellucid, iridescent. Length, 0°2; width, 0.2. Sowth-Carolina. 
A. aqualis. (Ip. Ib. Vol. 2, p. 307; Am. Conch, pl. 28.) Shell orbicular, slightly oblique, polished, 
with numerous concentric wrinkles near the margin, obsolete on the disk and umbo. Primary 
teeth two in the left valve and one in the other, which has no lateral tooth. Color, white. Length, 
04. Not uncommon on the Southern Coast. 
FAMILY MYADA:. 
Suey often inequivalve, inequilateral, gaping at both extremities or at one only. Hinge 
with an irregularly shaped tooth or teeth in one valve, received into an excavation in 
the other, with an intermediate ligament. 
Oss. This group is ‘formed of part of the Family Pyloridés of Blainville, and embraces 
portions of the two families Myazres and Corbulées of Lamarck. It is represented on our 
coast under three generic forms. 
GENUS PANDORA. Bruguiéres. 
Animal with the mantle in the form of a sheath, and terminating behind in two tubes united 
only at their bases, rather short, open in front for the passage of a large triangular foot, 
which is thick and dilated at its end. Gills large, free behind; or the two pair are united, 
and terminate in a point in the tube. Labial appendices rather large, triangular, not 
striated. Shell thin, pearly within, transversely oblong, inequivalve, inequilateral : right 
valve flattened ; left valve more convex. Hinge with two diverging teeth in the flat valve, 
and corresponding grooves in the other. 
