TRIBE MYTILACEA. 233 
Section. A. 
Having the general appearance of M. Modiolus t.e. smooth and sub- 
cuneiform. 
MM. Moptotus.* Turton. Biv. 199.t. 15. f. 3. (young)—Gould 
Mas 123.—Myrtitus M. Lin. Sys. 12 ed. 1158. (certo).—Pen. 4. 
238. t. 69.— Don. t. 23.—Da. Cost.t.15. f. 5.—D. p. 314.—W. 
t. 12. f. 31.—Mont. 163.—Mop. Vutearis. F. p. 412.—M. Bar- 
satus. Macg. Ab. 238.—Mytitus B. Mont. 11. (not Lin. certo). 
Ovate oblong, ventricose, gradually widening anteriorly, cuticle of 
an uniform yellowish or brownish chesnut or black, substance thick, 
whitish with a darker or lighter tinge of livid purple; hinge margin 
ascending and straight for about half the length of the shell, um- 
bonal ridge very distinct near the beaks which project and curve 
outwards ; posterior extremity very short and narrow: anterior 
edge never incurved.—Var. M. Parpuana Lam. 1.—Bl. t. 64. f. 3. 
(good), Transversely produced, very narrow, posterior side much 
attenuated. 6. N. Europe, N. America. The young are generally 
bearded with filaments which do not spread at the base as in the true 
Barbatus. The Giszsu. of Turton’s Bivalves (if this byssus be not ex- 
traneous) may be distinguished by its filaments being serrated on one 
edge 
M. Barsata. Lam. 14.—Philippi p. 70.—Mytinus B. Lin. 
1156 certo.— Gualt. t. 91. H. mid. fig. Subtriangular, not at all 
ventricose, under a concentrically imbricato-rugose ferruginous 
cuticle, rich red covered with lanceolate barbations, whose edges are 
not serrated except on the extreme posterior area, where the shell 
is white ; dorsal edge rather short, forming an obtuse angle with the 
much extended edge of the flattened anterior side; posterior side 
all but obsolete, the terminal beaks forming an acute angle with the 
ventral margin: inside white stained with purplish red anteriorly : 
ligament quite internal. 2. Mediterranean and N. Seas. Almost a 
Mytilus, and very different from the young of M. Modiolus. This is 
the true Barbatus of Linneus as I have ascertained by comparison 
with his specimens. 
M. Tutiea Lam. 2. Sow. G.— Reeve Sys. t. 101. f. 5.—Knorr. 
4.t. 15. f. 3.—E. 221. f. 1,—List. t. 759. f. 198. Oblong, thin, 
inflated, under a yellow cuticle, which posteriorly becomes dark 
chesnut, rayed with purplish red on the broader side ; hinge mar- 
gin much elevated but short, the anterior dorsal line thence sloping 
concavely to the obtuse anterior extremity ; ventral edge incurved 
in the middle ; beaks touching: posterior end narrow but promi- 
nent; umbonal ridge xot obtusely angulated. 2. America, W. 
Indies. Var. (!) from New Holland. Less elongated, the rays 
united into one broad anterior streak, anterior edge uniting with the 
ventral in an uninterrupted convex line 15. The variety of La- 
marck which I feel sure is a distinct species, is described from an exa- 
