TRIBE NYMTHACEA. 71 



hinge nearly central, with two small indistinct cardinal teeth in each 

 valve, and no lateral. -| . . J. — W. Europe. 



T. Bimaculata.* Lin. 1 150.— D. p. 101.— Lam. 52.— Ch. 

 f. 127.— E. t. 290./ 9.— Don. t. 19./. l.—Turt. B. p. 184.— 

 'Wood. G. C. t. 45. f. 6.—W. t. 4. / 83. Triangularly rounded, 

 broad, smooth, whitish with two oblong crimson spots on the inside ; 

 lateral teeth in both valves. — Variety. Pale violet without the 

 spots. {Ch. f. 132. a.) — Var. Uniform orange. — Var. Orange 

 with interrupted linear purple rays. — Var. Pink with the two 

 spots. — Var. Uniform pink. Hinge with two lateral teeth in both 

 valves, f. — W. Indies. 



T. Sexradiata.* Lam. 53.— T. Bimaculata variety. D.p. 

 }01.—E.t. 290. / 10.— Ch. f. 132. b. Triangularly rounded 

 inequilateral, whitish, with six brownish blue somewhat interrupted 

 rays : darker within. — Variety. With violet arrowheaded spots 

 disposed in rays.— (Turt. B. t. 8./ 5.) ^ . . f . — W. Indies. 



T. Ostracea. Lam. 54. — E. t. 290. /. 13. Roundish-ovate, 

 thin, flattened, whitish grey, with transverse striae, which are fine at 

 the beaks and coarse and ridge-like at the margin : anterior side 

 truncated, and with two folds. — Size of T. Tenuis. — India. 



T. Lata. Quoy. Ast. t. 81./. 8, 9, 10. Ovate, broad, depressed, 

 inequilateral, posterior side the shorter angulated, transversely 

 striated ; white with elegant interrupted rays of red ; beaks acute 

 and purple ; margin with alternate white and red spots ; yellow 

 within. — South Seas. 



T. Nasuta. Con. Jour. A. N. S. Phil. 7. p. 258. Ovate, 

 compressed, smooth, dull, posteriorly dilated ; anterior side cunei- 

 form, extremity truncated, much above the line of the ventral edge : 

 fold carinated on the upper valve ; beaks central, slightly prominent; 

 epidermis brown, extremely thin and deciduous, finely wrinkled. 

 If- . . If. — California. 



T. Edentula. Brod. and Sow. Z. J. 4. — Beeehey Zool. t. 41. 



f.5.and44.f. 7 '.—Lis.t. 406./252. ?— An. Ch.f. 74. 1—E. t. 290. 



/. 3. ? Obovate, posteriorly longer, depressed, anteriorly shorter and 



sub-angulated ; rather inequivalve, concentrically striated, whitish ; 



ligament large : cardinal teeth obsolete, no lateral ones. 2 . . 2\. — 



Behring's Straits. 



T. Alta. Conr. Journ. A. N. S. Phil. 7. p. 258. Sub-oval, 

 approaching to sub-orbicular, slightly ventricose, dull, roughish, 

 yellowish white, equilateral, with distinct prominent lines of growth, 

 posteriorly obtusely rounded ; deeper valve anteriorly biangulated, 

 the other with an angular groove ; margin broad direct slightly 

 emarginate at its extremity towards the base ; cardinal plate broad, 

 teeth long and prominent. — l^..lf. — California. — Outline not 

 unlike E. t. 231. /. 1. 



T. Flexuosa, Say. Jour. A. N. S. Phil. 2. p. 303.— Subor- 



