MESODESMA.— Plate IV. 



concentrically grooved and densely ridged, ridges 

 slightly raised on the posterior area ; yellowish-white. 



Deshayes, MS. (Mus. Cuming.) 



Hab. ? 



An equilateral triangularly transverse species, rather 



densely ridged and grooved. 



Deshayes, MS. (Mus. Cuming.) 



Hab. ? 



A nearly equilateral transverse shell, of simple character. 



Species 28. (Mus. Cuming.) 

 Mesodesma triquetka. Mes. testa oblique triangulari, 

 crassd, valdei/ibbosd, inaguilaterali, latere postlco brevi, 

 rotmdato, antico lonyiore, an-gulato-producto, area 

 lata, coiicavo-cordatd, uiitboidbm parvis, subdistatdibus, 

 ligamento subextemo ; sordide alba. 



The three-couneked Mesodesma. Shell obliquely 

 triangular, thick, very gibbous, inequilateral, posterior 

 side short, rounded, anterior longer, angularly pro- 

 duced, area broad, concavely heart-shaped, umboes 

 small, rather distant, ligament subexterual; dead 

 white. 



Hanley, Pro. Zool. Soc. 1843. p. 101. 

 Anapa triqiietra, Gray. 



Hab. Van Diemen's Land. 



e !, A gibbous Mulinia-\\Vt species, with an unusually large 



and broad anterior area, typically distinct from any other 



species of the genus. 



Species 29. (Mus. Cuming.) 



Mesodesma mitis. Mes. trigono-ovatd, subventricosd, 

 stibaquilaterali, latere atitico paulo breviore, vix trtin- 

 cato ; albd, irregulariter sulcato-striatd. 



The mild Mesodesma. Shell triangularly ovate, rather 

 ventricose, nearly equilateral, anterior side a little the 

 shorter, scarcely truncated ; white, irregularly groove- 

 striated. 



Species 30. (Mus. Cuming.) 

 Mesodesma Layakdi. Mes. testa trigono-ovatd, sub- 

 compressd, vix cequilaterali, latere antico obtuse trian- 

 gulari, latiore ; albidd, pallida violaceo-tiiictd, irregu- 

 lariter striatd, striis ad latera rugosis, intus purpuras- 

 cente-violaced. 

 Layard's Mesodesma. Shell triangularly ovate, rather 

 compressed, scarcely equilateral, anterior side obtusely 

 triangular, broader ; whitish, tinged with pale violet, 

 ii-regularly striated, striae rough at the sides, interior 

 purple-violet. 

 Deshayes, MS. (Mus. Cuming.) 

 Hah. Ceylon ; E. L. Layard. 



Chiefly distinguished by its delicate purple-violet co- 

 louring. 



Species 31. (Mus. Cuming.) | 



Mesodesma pr^cisa. Mes. testd trigoiw-oblongd, craud, I 



gibbosiusculd, valde iiicEqidlaterali, latere antico ab- \ 



rupie truncato, postico producto, rotundato ; albidd, ! 

 ferrngineo-fusco tinctd, ad marginem epidermide ferru- ; 



gineo-nigricante indutd. 

 The chopped Mesodesma. Shell triangularly oblong, 



thick, rather gibbous, very inequilateral, anterior side 



abruptly truncated, posterior produced and rounded ; 



whitish, tinged with rust-brown, covered at the mar- i 



gin with a rust-black epidermis. 

 Deshayes, MS. (Mus. Cuming.) 

 Hab. Van Diemen's Land ; Gunn. 



A rather solid rust-stained shell, very abruptly truncated] 

 at the anterior end. 



