253 



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

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

 nearly smooth, or marked in fresh specimens with distant striulae 

 towards the extremely arched ventral margin ; dorsal edges nearly 

 straight and strongly slopiug 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 

 almost obsolete ; inside usuaDy yellow or rose-coloured at the um- 

 bones ; a small lunule ; teeth as in Nux. 



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



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

 texture even in the youngest individuals. The ligamental edge 

 being nearly straight, easily separates it from Plnguis, where it is 

 decidedly convex. 



57. Tellina casta (pi. lvi. f. 9,) Hanle//, Zool. Proc. 1844. 



T. testa, obovali, tenuissima, subinsequivalvi, subinaequilaterali, 

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

 gine ventrali maxime arcuato ; dorsah utrinque subrecto, subsequa- 

 liter satisque declivi ; extremitate postica angusta, biangulata ; 

 ligamento angustissimo, subinfosso; natibus acutis; flexura ven- 

 trali costaque umbonali distinctis ; dentibus ut in Nice. 



Oboval, extremely thin, sbghtly inequivalve, nearly equilateral, 

 convex, glossy, pellucid, white, 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 ; Ugament ex- 

 tremely narrow and scarcely, if at all, 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. lvi. f. 10.) Lin. Sys. 1119. Poli. 

 Test. Sic. vol. i. 1. 14. f. 17. ; Lam. 2nd ed. vol. vi. p. 209 ; Phil. 

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

 Lucina balaustina, Paj/r. Cat. Cors. t. 1. f. 21, 22. 



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

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

 nonnunquam lineis elevatis concentrice striata ;^margine ventrah 

 arcuato ; dorsali utrinque convexo aut convexiusculo, satisque de- 



