TRIBE MACTRACEA. 39 



ERYCINA. 



Transverse, sub-inequilateral, equivalve, rarely gaping ; with two 

 primary teeth, unequal , diverging, with a pit interposing ; lateral 



/. 9, 0, 1. Crassatella Ovata. W. S. Mact. f. 11. Ovate-ob- 

 long, transverse, subaequilateral, thick, solid, greenish-yellow, 

 smooth ; interior white, hinge thickened, ligamental pit deep and 

 produced at the base, teeth nearly equal. 2\. — Australia ? 



M. Donacilla.* Desh. — Amphidesma D. Lam. 2. — Donax 

 Plebeia, Mont. t.f. b.f. 2.—JD. p. 102.— W. t. 6./. 10.— Ery- 

 cina P. Sow. G.f 3.— Reeve. £.45./. 5. Ovate triangular, wedge- 

 shaped, smooth, glossy; posterior side very short and obtuse; variable 

 in colouring, being sometimes yellow, pale with three or four ches- 

 nut or dark rays, and often yellow with a broad central white ray, 

 edged with chesnut, inside yellowish. J. — Mediterranean, Gulf of 

 Tarentum. 



M Cornea. Desh. — Amphidesma C. Lam. 4. — Del. t. 4. /. 

 5. Ovate-triangular, reddish horn-colour, unspotted, posterior side 

 very short. 1. — Mauritius 



M. Glabella. Desh. — Amphidesma G. Lam. 13. — Bl. t. 78. 

 /. 6. Suboval, white, semitransparent, small and transversely 

 striated ; anterior side the shorter and obliquely truncated, -§. . . -J. 

 — New Holland. 



M. Solenoides. Gray. — Erycina S. King in Z. J. 4. — Grif. 

 Guv. mol. t. 22. /. 1. Elongated-subelliptic, thin, obtuse at both 

 extremities, and much produced, closely substriated concentrically, 

 whitish under a greyish brown epidermis : ligamental pit project- 

 ing much below the hinge margin, \±. .2. —S. America. 



M. Arctata. Gould. Mas.f. 39. — Mactra A. Conr. Jour. A. 

 N. S. Phil. 6. t. 11./ I.— Reeve. £.45./ 3 Wedge shaped, sub- 

 ovate, smooth, thick, compressed; anteriorly very short, obtusely trun- 

 niated directly, posteriorly produced with the end margin rounded, 

 ventral edge arcuated ; cuticle golden yellow, reflecting a metallic 

 lustre ; cartilage pit triangular and profound ; lateral teeth striated 

 transversely, the posterior one elongated, f . .1^. — Massachussets, 



M. Deaurata.— Mactra D. Turt. Biv. t. 5./ 8. p. 71.— 

 Mac. Denticulata. W. S.f. 9. — Grif Cuv. mol. t. 22. /. 

 2. — An. Mes. Jauresii of Mag . deZ. and Gould Mas. Elon- 

 gated, wedge-shaped, convex, thick, dirty white with ridges of 

 growth under a tawny and hornlike epidermis, which usually reflects 

 metallic colours : elongated side rounded, shorter side obtusely, 

 but not directly truncated : muscular scars of teeth very strong, 

 the latter and their receptacles strongly striated. 



Compare with these the British Donax Castanea (Mont. t. 17. 

 f. 2.— D. p. 152.— W. t. 6. f. 10.) which evidently belongs to this 

 genus. We have copied the figure of Montague. 



