202 CYEENIDJE. 



Mactra, Brongniart, Mem. Vincent, 1823, p. 81, pi. 5, fig. 8. 

 Gelonia, Gray, Synop. Brit. Mus. 1844, p. 75. 

 Cyrena. Prime, Cat. Corbiculidae, 1869-70, p. 141 ; Clessin, in 

 Martini & Chemnitz, 1879, p. 101. 



TYPE, Cyrena ceylonica (Chemnitz) ; Ceylon. 



Range. Tropical and subtropical regions of Asia, Africa, 

 Oceania and Australia. 



Shell oval or subtrigonal, rather convex, solid, covered with a 

 periostracum generally of a brownish-green or yellow hue ; each 

 valve bearing three somewhat divergent cardinal teeth ; the right 

 valve bearing four unequal short lateral teeth, of which the 

 anterior are more nearly situate to the cardinals than the posterior, 

 and the outer smaller than the inner ; the left valve bearing but 

 two lateral teeth, one anteriorly and one posteriorly ; pallial line 

 generally entire. 



Animal with very short siphons, large, compressed, trigonal foot, 

 gills of unequal size, and triangular labial palpes. 



325. Cyrena ceylonica (Chemnitz). 



Venus ceylonica, Chemn. in Martini & Chemnitz, vi, 1782, p. 333, 



pi. 32, fig-. 336. 



Venus coaxans, Gmelin, Syst. Nat. 1788, p. 3278, fig. 336. 

 Cyclas zeylanica, Lamarck, Ann. Mus. Hist. Nat. vii, 1806, p. 420. 

 Cyrena zeylanica, Lamarck, An. sans Vert, v, 1818, p. 554; Prime, 



Cat. Corbiculidae, 1863, p. 6. 

 Cyrena ceylonica, Lamarck, Prime, Cat. Corb., 1869-70, p. 143, 



Gen. Cyrena, no. 12; Clessin, in Martini & Chemnitz, 1879, 



pp. 102-103, pi. 17, figs. 1 & 2, pi. 18, figs. 1 & 2. 

 Cyrena ceylanica, Sowerby, Conch. Icon, xx, 1878, pi. 19, sp. 11. 



Shell large, solid, subtrigonal, subcompressed, high, subequi- 

 lateral, covered with a thin, yellowish epidermis, with fringed 

 striae : posterior side obtusely two-angled, rather concave in front 

 of the anterior angle ; flattened, much sloped behind the posterior 

 angle ; anterior side rather short, latero-dorsal flattened, sloped. 

 (Sowerby.) 



Hob. Ceylon. 



The dimensions here given are those of three specimens in the 

 British Museum Collection : 



1. 2. 3. 



Long 62 51 47 mm. 



Lat. 65 50 48-5 mm. 



Diam. 35-5 27'25 27 mm. 



326. Cyrena impressa, Desliayes. 



Cyrena impressa, Deshayes, P. Z. S. xxii, 1854, p. 18 ; Cat. Brit. 

 Mus. 1854, p. 249. 



Original description : Testa ovato-subcirculari, obscure sub- 

 quadraugulari, valde inaequilaterali, turgida, mediocriter crassa; 



