FAMILY ANATINIDZ — THRACIA. 237 
THRACIA CONRADI. 
PLATE XXVIII. FIG. 284. 
Thracia declivis. Conrap, Am. Marine Conch. p. 44, pl. 9, fig. 2 (exc. syn.). 
a conradi, CovuTuovy, Bost. Jour. Nat. Hist. Vol. 2, p. 153, pl. 4, fig. 2. 
T. id. Russet, Essex Jour. Nat, Hist. Vol. 1, p. 75. 
fig id. Goup, Invertebrata of Mass. p. 50. 
Description. Shell thin, fragile, ventricose, rounded in front, narrowed and subtruncate 
behind. Beaks prominent, with one or more obtuse carinations extending to the angle of the 
basal and posterior margins ; the beak of the right valve perforated to receive the points of 
the other. Right valve more convex, and extending somewhat beyond the left : valves slightly 
gaping. Hinge toothless, but represented by strong rounded eminences. Surface with a 
thin epidermis, and with concentric undulated strie. Palleal impression with an acute angu- 
lar sinus: no ossiculum. 
Color. Epidermis light brown ; within white. 
Vertical axis, 2°2; transverse ditto, 2°7. Diameter, 1°4. 
This is one of the largest species of the genus, and is found along the coasts of Rhode- 
Island, Massachusetts and Maine. Mr. I. Cozzens assures me that he has obtained it in 
Long island sound, along the shores of Connecticut, so that in all probability it exists on the 
shores of this State. 
(EXTRA-LIMITAT.) 
Genus Ampuipresma, Lamarck. Shell inequilateral, transverse, suboval or somewhat rounded: sides 
slightly gaping. Hinge with one or two cardinal teeth, and anarrow groove for the internal 
ligament; external one short ; internal one fixed in the internal grooves. 
A. flexuosa, (Lam. Vol. 2, p. 344. Trrxina id. Monracu, Test. p. 72.) Shell suborbicular, 
thin, convex, pellucid, fragile, with minute irregular concentric strie. A remarkable furrow 
extends from the apex parallel to the cartilage-slope, and forms a deep curve in the margin at its 
termination. Hinge with an obsolete tooth. Color, white. Length, 0-6. On the authority of 
Mr. Redfield, this has been found on the coast of Massachusetts. 
A. transversa. (Say, Conch. pl. 28.) Shell transversely short, oval, nearly equilateral, compressed, 
a little gaping. Hinge nearly central: margins subequally rounded behind and in front; the 
former somewhat more obtusely so. Basal margin regularly rounded without any undulation in 
front: apex obtuse, but little prominent. Cardinal teeth two; fosset dilated, fusiform, abruptly 
very narrow at the beaks: lateral teeth none. Posterior muscular impression very slender and 
elongated. Color, tinged with yellowish. Width, 1°5. Long Island Sound? Southern Coast. 
A.? punctata. (Say, Ac. Sc. Vol. 2, p. 308.) Orbicular, with numerous minute concentric wrinkles 
and very numerous minute punctures. No lateral teeth ; two primary teeth in each valve, of which 
one has a deep groove: within, a small rim or projecting line runs near the edge from the hinge 
to the basal margin. Color, white. Length, 0:3; width, 0°3. Southern Coast. 
A. orbiculata. (In. Ib. Vol. 2, p. 317-) Shell orbicular, somewhat compressed: beaks nearly central, 
and a little prominent; valves slightly wrinkled transversely. Hinge with two lamellar teeth ; 
