253 



Rounded-subtrigonal, solid, rather inequivalve, nearly equila- 

 teral, ventricose, of a glossy yellowish wliite, or pale rose-colour, 

 nearly smooth, or marked in fresh specimens with distant striulse 

 towards the extremely arched ventral margin ; dorsal edges nearly 

 straight and strongly sloping on either side ; posterior side atten- 

 uated, almost beaked, and obtusely acuminated at the extremity ; 

 ligament extremely narrow and sunken ; umbones tumid ; beaks 

 distinct, prominent, and incurved ; fold distinct ; umbonal ridge 

 abnost obsolete ; inside usually yellow or rose-coloured at the um- 

 bones; a small lunule; teeth as in Nux. 



Isle of Aimaa, South Seas, and Isle of Burias, Philippines. 



Is closely allied to Nux, Pingids and Casta, but of a stouter 

 texture even in the youngest individuals. The ligamental edge 

 being nearly straight, easily separates it from F'mguis, where it is 

 decidedly convex. 



57. Tellina casta (pi. Ivi. f. 9,) Hanley, Zool.Proc. 1844. 



T. testa obovah, tenuissima, subinsequivalvi, subinsequilaterah, 

 pellucida, convexa, nitida, extus intusque Candida, laevigata ; mar- 

 gine ventrali maxime arcuato ; dorsaH utrinque subrecto, subsequa- 

 liter satisque decHvi; extremitate postica angusta, biangulata; 

 ligamento angustissimo, subinfosso; natibus acutis; flexuia ven- 

 trali costaque umbonaH distinctis ; dentibus ut in Niice. 



Oboval, extremely thin, slightly inequivalve, nearly equilateral, 

 convex, glossy, pellucid, wliite, smooth ; ventral margin extremely 

 arcuated ; the dorsal on either side nearly straight, moderately and 

 nearly equally sloping ; beaks acute ; fold and umbonal ridge dis- 

 tinct ; posterior extremity narrow and biangulated ; ligament ex- 

 tremely narrow and scarcely, if at aU, projecting ; teeth as in Nux. 



Singapore. 



Bears some resem blance to Nux, but the shape is less broad, 

 the ventral edge decidedly arcuated, the dorsal edges less convex 

 and shorter, and the umbones colourless. 



58. Tellina balaustina (pi. Ivi. f. 10.) Lin. Sys. 1119. Poli. 

 Test. Sic. vol. i. 1. 14. f. 17. ; Lam. 2nd ed. vol. \A. p. 209 j^Phil. 

 En. Mol. Sic. vol. i. p. 25 ; Hani. Des. Cat. p. 72. sup. t. 9. f. 17 ; 

 Luciiia balaustina, Payr. Cat. Cors. t. 1. f. 2l, 22. 



T. testa obovata, aut suborbiculari, solidiuscula, convexa, iiiti- 

 diuscula, albo-flavescente, radiis angustis rubris ornata, sublccvigata, 

 nonnunquam lineis clevatis concentrice striata ; margine ventrali 

 arcuato ; dorsali utrinque convexo aut convexiusculo, satisque de- 



Q 



