TRIBE MYTILACEA. 247 



violet undents epidermis, and elosely striated concentrically : pos- 

 terior side straight, anterior obtusely angulated, beaks white and 

 curved, furnished with an internal tooth in each valve. 5|. S. 

 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 scalar'iform. 



M. Canalis. Lam. 15. — List. t. SCO./. 199. Obion g smoothish', 

 bluish black, anterior margin channelled, posterior white flattened 

 and nearly straight : beaks slightly divergent, var. E. t. 215. 

 Broader and the beaks shorter. 5. Jamaica. 



M. Ungulatus.. Lam. 16. — Humboldt and Bonpl. Zool. t. f. — 

 Gualt. t. 91, E.—Ch.f 756 1—W. t. 12. /. 23 ? Large, somi-ovnte, 

 blackish violet, curved anteriorly, straight and flattened posteriorly : 

 within white, margined with violet, a tooth or two under the beaks 

 6|. " Not presenting the posterior incurvation of the following spe- 

 cies''" This is not the Uagidatus of Linnceus system. (jp. 11 57. )for he 

 states that the posterior margin is injlexed. His own specimen seems 

 a monstrosity bearing much resemblance to Lister. 369. to which he 

 refers in his M.S.S. It is not however that, species. 



M. Violaceus. Lam. 17. — E. t. 216. /. 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. 4^. Atlantic, fyc. 



M. Viridis. Lin. — M. Viridis Chinensis Chem. 11. f. 2022, 

 3. (good)— List. t. 363. f 204.— M. Opalus. Lam 18. 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, young. — 

 M. Viridis. 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 Linnceus. I am certain of the correctness of synonyms. 2 



2 Probably the young is the same species with M. Smaragdinus. 

 M. Deshayes states, that that species is the same as Opalus which I 

 cannot doubt is the Viridis. I give however its characters. 



M. Smaragdinus. 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. — India. 



