24t> TESTACEOUS MOLLUSCA. 



not at all flattened nor incurved ; hinge margin short, not forming a 

 distinct angle with the anterior ventral : within dark purple, margin 

 crenulated hinge with few denticles. 1. — Senegal. 1 



In my specimen there were 3 denticles in one valve and 4 in the 

 other, the beaks were rather obtuse. 



M. Polyodontus. Quoy. A st. t. 78. f. 15. 6. Oblong, angu- 

 lated, reddish, adorned with curved brown concentric lines, with 

 coarse granular waved longitudinal ribs : within violet, the hinge 

 margin with 8 or 10 nearly equal denticles at the extremity of the 

 ligament. New Zealand. Not unlike Magellanicus. 



M. Hamatus. Say. Jour. Philad. 2. p. 265. — Amer Conch, t. 

 50. Ovate-subtriangular, not very thick, moderately convex, with 

 very numerous longitudinal subcrenulated diverging elevated sulci, 

 which are about as wide as the interstices and often forked at their 

 extremities; epidermis yellow, outer surface pale purplish brown, 

 inner rich purple, whitish at the margin which is strongly crenulated ; 

 hinge margin convex, of a moderate length, not forming a distinct 

 angle with the anterior ventral : posterior side much incurved and 

 somewhat flattened ; beaks much inclined inwardly. Not unlike 

 Bilocularis exteriorly. 1|. Gulf of Mexico. New Orleans. 



M. Arealis. Menke Synop. Met. Moll. Oval-triangular, ante- 

 riorly angulated, posteriorly straight ; brownish black with longitiu- 

 dinal grooves on both sides, the central area with most delicate trans- 

 verse trias. 6 . . 1 1. lines. "Found along with Exustus." Can this be the 

 same shell with the Lateralis of Say.? I have never seen either, but 

 the descriptions are not at variance. 



M. Granulatus. Nobis. Zool. Proc. 1844. Triangularly-oval, 

 thick, extremely tumid, ochraceous yellow, with numerous distinct 

 rounded granulated radiating ribs, which are narrower than their 

 interstices, usually bifurcated at their extremities, becoming con- 

 siderably narrower at the very flat and broad posterior slope ; beaks 

 greatly incurved : hinge margin short and convex, forming a rounded 

 off angle with the very arcuated and dilated anterior margin ; ven- 

 tral edge moderately incurved : within uniform nacreous white, the 

 margin strongly crenulated and the hinge with two teeth in one 

 valve, a single one in the other. §••-§•• $• America. 



** Without radiating sulci. 



M. Latus. Lam. IS. — E.t. 216. f. 4. Oblong ovate, pale 



1 This species is not unlike Schrolers figure of Strtatulus (Ein. 

 t. 9. f. 10. copied W. t. 12. f. 19.) I have not seen the species 

 which is professedly that of Linnaeus. Mant. 518. — D. p. 308. 



2 To this section belong also — M. Bifurcatus. Com: Jour. 

 Philad. 7. t. 18. /, 14,— M. Calteornianus. Conr. J. Philad. 7. 

 p. 242. — M. Lateralis, Say. (if it be not a Modiola) Jour. Phi- 

 ad. 2. 



