MACTEA.— Plate XII. 



sulcata, postice lavigatd; lunula, aredque latiusculis, 

 plicaio-striatis. 



The half-striated Mactra. Shell transversely ovate, 

 swollen, gibbous, nearly equilateral, sides rounded, 

 the posterior rather the longer, livid white, shining, 

 purplish at the umboes, partially covered with a thin 

 straw-coloured epidermis, anteriorly grooved, striated, 

 posteriorly smooth ; lunule and area rather broad, 

 plicately striated. 



Deshayes, Pro. Zool. Soc. 1854. 



Ha6. — ? 



Of rather subglobose form, 

 anterior half of the shell. 



groove-striated over the 



Species 56. (Mus. Cuming.) 



Mactra maculata. Mad. testa trigono-ovatd, tenuicnld, 

 compressd, iiiaquilaterali, trausversim irregulariter 

 teimistriatd, albidd, ferrugineo-fuscescente marmoratd, 

 postice castaneo-tinctd, latere antico brevi, rotundato, 

 postico declivi, attemiato-angulato ; lunula subindis- 

 tinctd, arm oblongd, punctulatd ; mnhonibus parvis, 

 approxmatis. 



The spotted Mactra. Shell triangularly ovate, rather 

 thin, compressed, inequilateral, transversely finely ir- 

 regularly striated, whitish, mottled with hght rust- 

 brown, posteriorly chestnut - tinged ; anterior side 



short, rounded, posterior slanting, attenuately an- 

 gled ; lunule rather indistinct, area oblong, dotted ; 

 umboes small, close. 



Chemnitz, Conch, vol. vi. pi. 41. f. 208, 209. 

 Mactra squalida, Lamarck. 

 Mactra setosa, Quoy. 



Eab. Philippine Islands ; Cuming. 



Of rather compressed form, produced on the posterior 

 side into a subattenuated angle. 



Species 57. (Mus. Cuming.) 



Mactra violacea. Mact. testa ovato-trigond, cequilate- 

 rali, tenui, fragili, postice paululum Mante, undique 

 intense violacea, transversim dense tenuissime striata, 

 epidermide tenui versus marginem ; lunula aredque 

 lanceolato-ovatis ; ?imbonibus approximatis. 



The violet Mactra. Shell ovately triangular, equi- 

 lateral, thin, fragile, a little gaping at the posterior 

 end, everywhere deep violet, transversely densely very 

 finely striated, with a slight epidermis towards the 

 margin ; lunule and area lanceolately ovate ; umboes 

 close. 



Chemnitz, Conch, vol. vi. p. 220, pi. 22. f. 213, 214. 



Hab. Malacca. 



A shell of light structure, always distinguished by its 

 uniform deep violet colouring within and without. 



