152 TESTACEOUS MOLLUSCA. 
* Margin entire. 
A. Tortrvosa. Lin. 1140.—D. p. 225.—Lam. 1.—Ch. 
Y024,.5.—FE...t.. 305% f. 1.—W. t. 9. f. 1.  Parallelopiped, 
obliquely keeled one valve more so than the other, twisted and 
almost equally broad throughout, but rather narrower at the 
posterior end, dirty or reddish white, with radiating strie and the 
anterior triangular portion strongly wrinkled transversely ; beaks 
small and recurved. 1..3—Indian Ocean. 
A. Semitorta. Lam. 2.—Fav. t. 51. f. OC. I.—W. S. 
t. 2. f. 2. Rather twisted, oblong elliptic, dilated, striated, the 
valves obsoletely carinated and rounded at their extremities ; beaks 
recurved. 31.—Van Diemen’s Land. 
A. Nom* Lin. 1140.—D. p. 226.—Lam. 3.—Ch. f. 529.— 
Bl. t. 65. f. 2.—Don. t; 158.» fo.1, 2.—E. t..303. f. ly & 
t. 305. f. 2.—W. t. 9. f. 2. Oblong rhomboidal, with fifty or 
sixty radiating grooves, the beaks incurved and very remote; 
whitish with diagonal broad parallel chesnut stripes ; the broad flat 
Space between the beaks with a few distant grooves radiating from 
each apex ; inside tinged with chesnut, the hinge with more than 
eighty teeth; the marginentire. 1..2.—Europe. The Atlantic. 
A. Navicunaris. Brug. E. p. 99.—D. p. 227.—W. t. 9. 
J 9.—Ch. f. 533.—E. t. 308. f. 3. Oblong rhomboidal, pale 
rufous with broad wavy chesnut diagonal stripes, with not more 
than thirty coarse radiating ribs which become broader at the sides, 
and fine intermediate strie: within brownish, crenulated on the 
sides of the margin and the hinge with not more than seventy 
teeth. 3..13.—St. Domingo. 
A. Terracona. Poli. t. 25. f. 12, 3—Lam. 4.—E. t. 308. 
J. 3.—Phil. p. 57. Oblong, with longitudinal riblike strize, trans- 
versely striated, anteriorly straight not emarginated and with an acute 
prominent keel, pale rufous never striped. 1.— Mediterranean. 
A. Impricata.* Brug. HE. p. 98.—D. p. 226.—A. Um- 
BONATA. Lam. 5.—A. Fusca. Don. 5. t. 158. f. 4.—W. t. 
9: 14.—Ch. f.. 532: — dist. t. 367: f. 207.—E. 305. f. 3. 
Ovate, posteriorly rounded, anteriorly forming an oblique angle 
with the hinge margin very ventricose brownish white within and 
without, with imbricated crowded decussated acute striae: liga- 
mental area hollow: margin gaping and quite entire. 1.— 
Jamaica.— Senegal. 
A. Srnuara. Zam. 6. Oval, obtuse at each extremity, with 
decussated strie, obliquely angulated, ventral margin sinuated and 
gaping. 12.—New Holland.—(Ahin to Helbingii and probably 
a variety.) 
A. Avennana. Lam. 7. Small, ovate, tumid, ventricose, 
shortened, with decussated striae, beaks arcuated, anterior slope 
