TRIBE MYTILACEA. 243 
M. Granputa. Totten in Sil. J. t. 26. f. 3.—Gould Mass. f. 87 
Obliquely rounded oval, rather inflated, brownish yellow, covered 
with minute lines of growth crossed by minute and crowded radia- 
ting lines, ligamenta! edge very short: beaks small and separate ; 
within nacreous white: margin crenulated. 9... 3.—U. States. 
M. Srricata. Nobis Zool. Pr. 1844. Small, oblong, fragile, 
pellucid, moderately convex, pale green with chocolate ziczac 
streaks, anterior side with radiating stria, posterior with a few lon- 
gitudinal riblets ; anterior edge convex: no dorsal angle. 
Phallipines.—Not unlike Discrepans in outline. 
M. Ciceruta Moller Index Mol. Grenl.—Mytitus Decus- 
satus? Mont.—Brit. Mar. Conch. f. 1.? Minute, subglobular, 
thin, subeequilateral, greenish yellow, slightly roughened by a de- 
cussation of minute radiating and concentric striz : margin finely 
erenulated. 4.—Greenland. Longer than broad.' 
MYTILUS. 
Longitudinal, equivalve : acute at the apex, affixed by a Byssus ; beaks 
acute, nearly straight and terminal; hinge lateral, generally 
without teeth: ligament marginal, and partly internal ; muscular 
ampression elongated, clavate and sublateral. 
Dey 
2 
* With radiating sulci. 

''To this section belongs the Myrinus Decussatus of Montagu 
which must be compared with the above species. 
See too, the M. Lirurata of Menke’s Synopsis, the Virrea of 
Moller (Moll. Green), the Styvosa of King (Z. J. 5.) the Curretius 
of Deshayes (Rev. Cuv. 1839) and the Cuenur of Recluz (Rev. 
Cuv. 1842.) which not being acquainted with, we are unable to put 
into any of our sections. 
The shell from which the genus Myrtitimerra of Conrad was 
constituted, is evidently a new and distinct species. The situation 
of the genus in the general system of nature, we know not; its pre- 
sent station being temporarily assigned to it, in accordance with 
Mr, Conrad’s statement, that it is allied to Mytilus and Modiola. 
MYTILIMERIA. 
Equivalve, suboval, thin; beaks subspiral: hinge edentulous, with a 
slight linear cavity under the beaks : muscular impressions two, ra- 
ther small: palleal impression mith a broad obtuse sinus. 
M. Norratu. Conr. Jour. Philad. 7. p. 247. t. 19. f. 5. Sub- 
oval, inflated, thin, fragile ; white with a very thin yellowish deci- 
duous epidermis. 1. California in sponge. The single valves have 
the appearance of Aplysie. 
R2 
