TRIBE MYTILACEA. 247 
violet underits epidermis, and closely striated concentrically : pos- 
terior side straight, anterior obtusely angulated, beaks white and 
curved, furnished withan internal tooth in each valve. 5}. 8. 
America.? 
M. Zonarius. Lam. 14.—E t. 217. f. 1. Elongated-oblong, 
narrow, much curved, antiquated, whitish with concentric violet 
zones : posterior side flat, sinuated, and white: within, white with 
the margin usually violet. The layers of growth are usually so 
raised as to render the surface scalariform. 
M. Canauts. Lam. 15.— List. t. 360,f. 199. Oblong smoothish, 
bluish black, anterior margin channelled, posterior white flattened 
and nearly straight: beaks slightly divergent. var. EH. ¢. 215. 
Broader and the beaks shorter. 5. Jamaica. 
M. Uneutarus.. Lam. 16.—Humboldt and Bonpl. Zool. t. f.— 
Gualt. t. 91, E.—Ch. f. 756 ?—W. t. 12. f. 23? Large, semi-ovate, 
blackish violet,curved anteriorly, straight and flattened posteriorly : 
within white, margined with violet, a tooth or two under the beaks 
63. ‘Not presenting the posterior incurvation of the following spe- 
cies” This isnot the Ungulatus of Linneus’ system.(p. 1157.) for he 
states that the posterior margin is infleced. His own specimen seems 
a monstrosity bearing much resemblance to Lister. 369. to which he 
refers in his M.S.S. It isnot however that species. 
M. Viotaceus. Lam. 17.—E. t. 216. f. 1.—Knorr. 5. t. 25. 
f. 1. Semi ovate, smooth, violet, the beaks and posterior side 
white, somewhat spotted with violet: anteriorly curved, posteriorly 
flattened inflected and subsinuated : three internal teeth under the 
beaks. 43. Atlantic. §c. 
M. Virivis. Lin.—M. Virivis Cutnensts Chem. 11. f. 2022, 
3. (good)—List. t. 363. f. 204.—M. Opatus. Lam18. Elonga- 
ted, sublunated, moderately convex, or rather depressed, rather 
thin ; umbonal ridge obsolete, epidermis brown, becoming bright 
green at the base, and at the successive stages of growth more or 
less tinted with that colour: posterior side not at all flattened, its 
margin incurved ; anterior arcuated and never at all angulated ; 
ligamental edge convex and rather short: interior brilliantly opa- 
line ; hinge with one not prominent tooth in each valve. younc.— 
M. Virivis. Lin. Mus. Ulric. 542.—Lin. Sys. ed. 12. 1158. 
Ovate, membranaceous, posterior edge not incurved, epidermis quite 
green : beaks tinged with crimson. South Seas: China? From the 
specimen of Linneus. I am certain of the correctness of synonyms. ° 

2 Probably the young is the same species with M. Smaracpinvs. 
M. Deshayes states, that that species is the same as Opalus which I 
cannot doubt is the Viridis. I give however its characters. 
M. Smaracoinus. Lam. 19.—Ch. f. 745. Subtriangular, flat- 
tish, the posterior side straight and the epidermis green : hinge with 
two teeth in one valve, one in the other: nacre opoline. 4.—Jndia. 
