APPENDIX. 845 



most minute crowded raised radiating lines ; valves very unequal in 

 size, the larger being produced in front and at the anterior ventral 

 margin, the umbones nearly even ; the smaller valve equilateral, its 

 unibonal ridge more sharply angular, and the area before it more 

 decidedly concave than in the other valve, f . 



Cokbula quadrata (t. 12, f. 36), Hinds, Z. P. 1843, p. 57. — 

 Reeve, I. Cor. f. 40. Transversely subquadrate, bluntly biangulated 

 in front, very short and rounded behind, very prominent at the 

 oblique and broadish umbones, very inequilateral, whitish both 

 within and without, concentrically wrinkled, granular ; umbonal 

 ridge arcuated and prominently carinated, the area before it con- 

 cave ; teeth slender, oblique, f . W. Indies. 



Corbula trigona (t. 12, f. 39), Hinds, Z. P. 1843, p. 58. — Reeve, 

 I. Cor.'f. 22. Small, oval-subtrigonal, subinequilateral, thickish, sub- 

 ventricose ; both valves smooth, both within and without whitish 

 (more rarely brown, or with a single obsolete band), subventrally 

 angulated on one side, subangulately rounded on the other ; ventral 

 edge arcuated and projecting in the larger valve. \. Senegal. 



Corbula nimbosa (t. 13, f. 58), Hani, (not Potamomya n. Hinds, 

 Z. P. 1843, p. 59 == O. n. Reeve, Ic. Corb. f. 31 = Mya labiata, 

 Maton, Lin. Tr.). — Potamomya, Sow. Man. f. 498, 9. — C. l. Reeve, 

 Ic. Corb.f. 28. Oval-subtriangular, subequilateral, rounded behind, 

 ventrally angulated in front, nearly smooth, solid, subventricose, 

 dirty (or reddish) white under a horny ochraceous epidermis ; inside 

 white. Valves very unequal, especially at the ventral margin, which 

 in the larger valve is solid arcuated and much projecting beyond the 

 other ; its umbo, likewise, is the more prominent. Neither lunule, 

 lozenge, nor carinated umbonal ridge. f...ltr. Singapore. The 

 epidermis of the smaller valve is apt to assume a clouded aspect; there 

 are some very indistinct radiating striolm on the other valve. 



Myochama Anomioides, p. 48, t. 12, f. 3. 



Pandora oblong a, p. 49, t. 10, f. 46 ... P. depressa, p. 49, t. 10, 

 f. 47 ... P. glacialis, p. 49, t. 10, f. 48 ... P. flexuosa, p. 49, t. 10, 

 f. 49 ... P. unguiculus, p. 49, t. 10, f. 50 ... P. trilineata, p. 49, t. 9, 

 f. 32 ... P. Ceylonica, p. 50, t. 10, f. 45. 



On Saxicava (p. 50). Conrad has subsequently referred his 

 S. Carditoides and Calif ornica (p. 51) to the genus Petricola. S.pho- 

 ladis (p. 51) is a variety of rugosa (of which S. distorta, Say, is a 

 synonym) : the types of S. Australis and its var. Veneriformis (p. 52) 

 remind one of Cardites (I did not see their hinges). The genus 

 Hiatella (p. 150) is redundant; its species must be transferred 

 hither. 8. costata of Menke's ' Synopsis ' is not a true Saxicava : 

 S. macrodon (Phil, in Zeit. Mai. 1851) and S. leg urn en (Desh. Rev. 

 Cuv. 1839) should be examined. 



2 D 



