82 TESTACEOUS MOLLUSCA. 



dark purple ray bordering the anterior slope near the beaks : no 

 posterior or lateral tooth. 1. — Africa. ? x 



** Inner edge crenated. 



D. Rugosa. Lin. 1127. — D. p. 159. — Rugosa in part. — 

 Lam. \7.—Knorr. 6. t. 28. /. S.—E. t. 262. /. 3.— Ch.f 250.— 

 W. t. 6. f. 3. Elongated, wedge-shaped, inflated, anteriorly ex- 

 tremely short obtusely and almost directly truncated, the slope 

 angulated at its edge and roughened by transverse coarse grooves 

 decussated by radiating striae : variable in colouring, being whitish 

 or pale drab, sometimes with purple rays, or reddish with deeper 

 zones, covered with simple rather fine radiating striae : ventral 

 edge not incurved and little arcuated. J . . lj. — S. America.* 



D. Striata. Lin. {not Chemnitz.) D. p. 151. — List. t. 

 376./. 2\9.—Kno?-r. 6. t. 7.f. 7 '. — Gualt. t. 89.D.—E. t. 262. 

 f. 5. Sub -triangularly cuneiform, inequilateral, covered with strong 

 radiating strise, variable in colouring but usually dull white or reddish 

 with darker concentric bands, posterior dorsal edge much sloping, 

 the ventral arcuated in the middle, but sub-incurved at the sides : 

 anterior slope sub-biangulated (sharply so at the umbonal slope) and 

 marked with strong radiating strise : margin internally dentated : 

 two lateral teeth in each valve. § . . 1J-. — West Indies. 



D. Cayennensis. Lam. 18. — Del. t. 6. /. 13. Somewhat 

 triangular, white slightly tinged with purplish, short and obtusely 

 truncated anteriorly, with fine longitudinal grooves, and the sides of 

 the anterior slope sub-biangulated : beaks reddish purple. — Guiana. 

 — Less tumid but akin to the last. 3 



D. Elongata. Lam. 19. — Adanson. t. 18. f. 1. — Seba. 3. t. 

 86. f. 10.? Transversely elongated and longitudinally grooved, 

 very obtuse anteriorly ; the grooves at the anterior end sub-denticu- 

 lated : violet within. — Variety. — Very pale fulvous and white 

 within. — W. Africa. 



D. Denticulata.* Lin. 1127.— L>. p. 151.— Lam. 20.— Ch. 

 f.T^.—E. t.262.f 7.— Don, t.24.—W. t. 6. /. 8. Ovate, 

 wedge-shaped and very obtuse anteriorly, with numerous fine 

 punctured longitudinal strise, white with purple rays : anterior slope 

 transversely wrinkled and the margin toothed ; purple within. 

 "1*2 ""lr* — Mediterranean and West Indies. 



D. Cardioides. Lam. 2\.—Ast. t. 81./ 17, 8, 9.— Del t. 



1 See too the Radiata of Schroeter (of which we have given a 

 copy) t.S.f 3. p. \04.—D.p. 155.— W. t. 6./. 17. 



2 D. Ringens, Lam. 16. is a Capsa. 



3 Delessert's figure of Cayennensis so well agrees with some 

 varieties of the preceding, that I can hardly venture to consider the 

 species distinct. 



