TRIBE NYMPHACEA. 79 
acute : interstices concave and transversely wrinkled ; one end de- 
pressed ; margin entire, lunule minute. Africa. 
L. Nurrati. Conr. Jour. A.N.S. Phil. 7. p. 255. t..20. f. 
2. Lenticular, broader than long, slightly compressed, cancellated, 
the concentric lines very regular, lamelliform, prominent ; pos- 
terior fold small and marginal; the extremity emarginate above ; 
ligamental edge little sloping, cardinal and lateral teeth distinct, 
inner margin minutely crenulated. 1 — Califorsha.'? Boe 
L. Cuttpreny. Gray Ann. Phil, 25. eH Fe ibaips ae. | 5* 
—Sow. Gf. 2/3 eene. t. 59. f.2.—TettinaC. W.S.¢.1.f. 1. is 28, 
Sub-orbicular, longer than broad, inequivalve, white, nearly smooth, 
sub-antiquated, very finely radiated, sub-striated. Length 3.— 
Brazil. 
L. Rucirera. Reeve. Z. P. 1835. Rounded, lenticular, 
rather convex, whitish, somewhat banded with reddish chesnut, the 
radiating striz elevated and crossing the concentric ; lunule tri- 
angular, impressed, minute: inside white. 2..21.—New Holland. 
—Not unlike Tigerina. 
DONAX. 
Transverse, equivalve, inequilateral; mith the anterior side very 
short and obtuse; two primary teeth in one or both valves ; and 
one or two lateral tecth, more or less distant ; ligament external, 
short, inserted at the posterior impression. 
Inner margin entire or nearly so. 
D. Scortrum. Jin. 1126.—D. p. 148.—Lam. 1.—. t. 
260. f. 2.—Ch. f. 242, 5, 6, 7.—B. t. 4. f. 1, 2.—W. ¢. 6. f. 1. 
Triangular with the anterior slope acute and flattish, greyish 
white, with usually a tinge of violet, and decussated elevated striae, 
which become abruptly more distant towards the posterior end; 
anterior depression somewhat heart-shaped and flat ; inside violet 
towards the hinge, and the margin not quite entire: hinge with a 
lateral tooth in each side. In old specimens the angular margin of 
the anterior slope is armed with vaulted scales: in young (D. Pvu- 
Bescens. Lin. 1127.—D. p. 149.—Ch. f. 24.—E. - 260. f. 1 
—Lam.2.—W. t.6. f. 2.) with serrated spines. 14,.24 India: 
D. Cungata. Lin. 1127.—D. p. 153.—Lam. 3.—Ch. f. 260. 
—List. t. 392. f. 231.—B. vignette, p. 52.—W. t. 6. fi 13. 
Ovate, wedge-shaped, compressed posteriorly, anteriorly abruptly 
truncated, convex and coarsely wrinkled transversely ; white or 
pale grey, rayed with rufous drab or dark violet, and very minutely 
striated longitudinally.—Variety. Rufous with white rays.— 
Variety. (D. Granosa. Lam. 8.) with the rays livid violet, and 
the angulated slope sub-granular. 1..14.—TZ'ranquebar. 
D. Gompressa. Lam. 4.—E. vol. 2. p- 96.—List. t. 391. f. 
