240 TESTACEOUS MOLI.TJSCA. 



one half to the anterior dorsal, the other to the ventral margin 

 T "L. . 2. — Philippines. 



Section D. 

 With radiating strice, ligamental edge forming an angle with the 



anterior margin. 



M. Sulcata. Lam. 9. — Bowd. El. Biv.f 64. — Arca Modiolus. 

 Lin.lUl — D. p. 231— Ch.f. 754,— W. t. 9./. 15— £. t.220.f.2. 

 — Mytilus Cubitus ? Say. Jour. Phil ad. 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 striae ; 

 ventral edge nearly straight ; beaks terminal ; within white tinged 

 with violet and the hinge margin crenulated. If. — W. Indies. 



M. Plicatula. Lam. 10. — Sow. G. — Reeve Syst. t. 101./. 7. — 

 Gould Ma*, p. 125. /. 87.— Mytilus Demissus. D. p. 314. — W. 

 t. 12,/. 30.— E. t. 220. /. 5.*— List, t. 356. f. 193.— Mod. Semicos- 

 tata. Conrad (jide Gould.) Much elongated, moderately ventricose, 

 posterior end compressed, prominent, and very narrow : ligamental 

 edge somewhat raised and much produced ; ventral strongly 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 a ngulated near 

 the depressed umbones, and becoming obsolete posteriorly, nacre 

 pearly white, cuticle varying from ochraceous to greenish bronze. 

 1|. . S\. — N. America. The hinge margin is not crenulated. 



"M. Puupurata 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. — Chili and Peru. In the 

 described specimen of the Museum of Paris, the raised sulci seem almost 

 crenulated by the striae of growth and the dorsal angle is not prominent. 



M. Costulata. Rnso. — Phil. p. 70. t. 5.f 11. Minute, ob- 

 long, smooth in the middle, with longitudinal riblike striae 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. \. . \ 

 Sicily. l( Allied to Discrepans four 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. 



