24.6 TESTACEOUS MOLLUSCA. 
not at all flattened nor incurved ; hinge margin short, not forming a 
distinet 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. Potyopontus. Quoy. Ast. 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 Jongitudinal suberenulated 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. 14. Gulf of Mexico. New Orleans. 
M. Areas. 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 trie. 6..11. lines. ‘Mound along with Exustus.” Can this be the 
same shell mith the Lateralhs of Say.? Ihave never seen either, but 
the descriptions are not at variance. ; 
M. Granutatus. 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, asingle one inthe other. 4..2%. iS. America. 
** Without radiating sulci. 
M. Larus. Lam. 13.—E.t. 216. f. 4. Oblong ovate, pale 

1 This species is not unlike Schrolers figure of Srrrarutus (Lin. 
1. 9. f. 10. copied W. t.12, f. 19.) Ihave not seen the species 
which is professedly that of Linnzeus. Mant. 548.—D. p. 308. 
2To this section belong also—M. Brrurcatus. © Conr. Jour. 
Philad. 7. t. 18. f. 14.—M. Catirornianus. Conr. J. Philad. 7. 
p. 242.—M. Lareranis. Say. (if it be not a Modiola) Jour. Phi- 
ii Be 
