240 TESTACEOUS MOLIUSCA. 
one half to the anterior dorsal, the other to the ventral margin 
45 - 2-—Philippines. 
Section D. 
With radiating strie, ligamental edge forming an angle nith the 
anterior margin. 
M. Sutcata. Lam. 9.—Bond. El. Biv. f. 64.—Arca Moptiowvs. 
Lin. 1141—D. p. 231—Ch. f. 754—W. t. 9. f. 15—E. t 220. f. 2. 
—Myritus Cusirus ? Say. Jour. Philad. 5. Oblong, the hinge mar- 
gin short, nearly straight ; much raised and forming a distinct angle 
with the anterior sinuous one; bluish white under a yellow epider- 
mis with slightly raised radiating sulci diverging at the obtuse 
anterior end, elsewhere covered with very fine longitudinal striz ; 
ventral edge nearly straight; beaks terminal ; within white tinged 
with violet and the hinge 1 margin crenulated. 12.—W. Indies. 
M. Pricatuta. Lam. 10.—Som. G.— Reeve Syst. i. LONoufeie 
Bie Mas. p.125. f. 87.—Mytitus Demissus. D. p. 314.—W. 
2, f. 80.—E. t. 220. f. 5.—List. t. 356. f. 193.—Mop. Semicos- 
tata. Conrad (fide Gould.) Much elongated, moderately ventricose, 
posterior end compressed, prominent, “and very narrow: ligamental 
edge somewhat raised and much produced; ventral stronely in- 
curved ; anterior slightly convex ; surface covered with raised sulci 
(which in the adult are forked at their termination) chiefly promi- 
nent in front of the umbonal slope which is obtusely angulated near 
the depressed umbones, and becoming obsolete posteriorly, nacre 
pearly white, cuticle varying from ochraceous to greenish bronze. 
13..34.—N. America. The hinge margin is not crenulated. 
"M. Purrurata Lam. 13.—List. t. 366. f. 206.2 Ovate with 
the hinge margin forming an elevated angle at its termination, lon- 
gitudinally grooved, deep purple except posteriorly and near the 
beaks, where it is whitish ; within purple, the margin crenated and 
the hinge margin with many teeth. 1.—Chiliand Peru. Inthe 
described specimen of the Museum of Paris, the raised sulci seem almost 
crenulated by the strie of growth and the dor salangle is not prominent. 
M. Costutata. Rasso.— Phil. p. 70. t. 5. f. 11. Minute, ob- 
Jong, smooth in the middle, with longitudinal riblike striz at the 
the sides, (the posterior sometimes though rarely smooth) reddish 
chesnut; anterior side closely bearded, the beard composed of long 
yellowish fibres ; ventral edge scarcely crenated at the sides. 4..4 
Steily. “Allied to Discrepans (cur Tumida) but much narrower and 
more tumid, the posterior side still smaller, the ligament very thick and 
strong with the margin adjacent to it deeply crenated on each side.” 
The figure represents this shell with a distinct dorsal angle at the extre— 
mity of its nearly straight hinge margin, and the ventral edge convex 
in the middle. 

