42 TESTACEOUS MOLLUSCA. 



p.7H.1 — W. t. 3. f. 17. Sub-orbicular, convex, depressed, thin, 

 purplish-white, with chesnut letter-like spots ; beaks contiguous 

 and rayed. — Africa? — Variety.^ C/i.f. 1957,8. 



A. Albellum. Lam. 5. Elliptic, thin, pellucid, smooth, white 

 and shining : both the cardinal tooth and the pit minute. |. — 

 South Seas. 



A. BoYsii.* Layn. 7.— Mactra B. Mo)it. t. 3. /. 7.—D.p. 

 143. — W. t. 6. f. 27. Transversely ovate, sub -triangular, de- 

 pressed, rounded at both ends, the beak considerably neai'er the 

 posterior extremity, sloping from the beaks on both sides, glossy, 

 pellucid, margin rather suddenly rounded ; hinge with a single 

 umbonal denticle in each valve, and broad, lateral, elevated teeth on 

 each side of it in one of the valves, i. — England.^ 



A. Tenue.* Lam. S.—Turt. B. p. 53.— Mactra T. B. 

 p. U3.—Bor. Cat. p. 33.- Mont. t. 17. /. 7.— W. t. G. /. 26. 

 Sub-triangular, equilateral, compressed, with the ventral margin 

 rounded, white, and concentrically wrinkled ; beaks produced and 

 central ; hinge with one bifurcated and a remote lateral tooth in one 

 valve, and a single plain one in the other. 1. — England, tj|V.* 



A. Prismaticum.* Lam. 10. — Mya P. B. p. 47- — Mont. 

 t. 26. ,/". 3. — W. t. 2. f. 21. Transversely oblong, attenuated at 

 one end and rounded at the other, irridescent, thin, transparent, 

 glossy, the margin slightly rounded, with obsolete concentric 



3 In general appearance, the genus Cumingia of Sowerby, bears 

 a close resemblance to this, and the cognate species formerly 

 grouped as Ligula by Montague. 



CUMINGIA. S01V. 



Inequilateral, equicalve, posterior side rounded, anterior rather 

 acuminated ; in each valve a single s)nall posterior cardinal 

 tooth, in one valve two lateral, but none in the other, a some- 

 what spoon-shaped pit containing the ligament: muscular scars 

 distinct, the posterior irregular and oblong, the anterior rounded, 

 the palleal with a large sinus. 



Mr. Reeve, in plate 49 of his elegant Conchologia Systematica, 

 figures the following species described by Sowerby in the Zool. 

 Proc. for 1833.— Mutica, Trigonularis, Lamellosa, Coarctata. Com- 

 pare with these the Californica of Conrad in Jour. A.N.S. Phil. 7 — 

 t. 17. f. 12. and the Tellinoides of Gould in his admirable work on 

 the Invertebrata of Massachussets. The latter shell we likewise 

 have figured. 



4 A. Phaseolina, Lam. 11. is a Thracia, A. Corbuloides, Lam. 12. 

 an Osteodesma, A. Glabrella, Lam. 13. a Mesodesma, A. Physoides, 

 Lam. 16. an Eryciua, and A. Flexuosa, Lam. 11. is the same as his 

 Lucina. 



