TRIBE MACTRACEA. 39 



EI^YCINA. 



Transverse, sub-inequilateral, equivahe, rarely gaping ; irith two 

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



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

 long, transverse, subsequilateral, 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. — Dor^AX 

 Plebeia, Mont. t.f. 5./. 2.—D. p. 102.— TF. t. 6./. 10.— Ery- 

 ciNA P. Sow. G.f. 3. — Iieeve t. 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. ^. — 3Iediterranean, Gulf of 

 Tarentum. 



M Cornea. Desli. — Amphidesma C. Lam. 4. — Del. t. 4. f. 

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

 very short. 1. — Mauritius 



M. Glabella. Desh, — Amphidesma G. Lam. 1-3. — Bl. t. 78. 

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

 striated ; anterior side the shorter and obliquely truncated. -|. .. ^. 

 — Neiri Holland. 



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

 Cuv. mol. t. 22. f. 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. 3Ias. f. 39.— Mactra A. Conr. Jour. A. 

 N. S. Phil. 6. t. 11./. l. — Reeve. t.Ao.f. 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. ^-. .\\. — Massaclms.^ets^ 



M. Deaurata. — Mactra D. 2\irt. Biv. t. 5./. 8. p. 71. — 

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

 2. — An. Mes. Jauresii of Mag . deZ. and Gould 3Ias. 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 I'eceptacles strongly striated. 



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

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

 geuus. We have copied the figure of Montague. 



