MACTRA. 



Plate XII. 



Species 51. (Mus. Cumiug.) 



Mactra achatina. Mad. testa, ovato-oblongd, elliptica, 

 compressa, subcBquilateraU, paUicle violaced, ad um- 

 bones purpurasceiitibus, maculk radiisque interruptli 

 lacteis pictd ; area limuldque indistinctii. 



The agate Mactra. Shell ovately oblong, elliptical, 

 compressed, nearly equilateral, pale violet, pui-ple at 

 the umboes, painted with milk-white spots and in- 

 terrupted rays ; area and lunule indistinct. 



Chemnitz, Conch. Cab. vol. ii. p. 218. f. 1957. 

 Mactra maculosa, Lamarck. 

 Mactra adspersa, Dunker. 

 Mactra maculata, Hanley. 



Hai. Philippine Islands. 



One of the most richly-coloured species of the genus, 

 being profusely mottled and rayed thi-oughout with violet 

 and flesh-rose. 



Species 52. (Mus. Cuming.) 



Mactea fasciata. Mact. testd ovato-trigotid, iiiaqtiila- 

 terali, tumidd, Icevigatd, opaco-albd, zonis violaceis 

 distantibiis notatd ; umbotiibus rufescente-molaceh ; la- 

 tere aniico obtuso, leviter concavo-impresso, postico ob- 

 tuse anguhito ; luniild hidistinctd, area sv.bampld. 



The banded Mactra. SheU ovately triangular, inaequi- 

 lateral, swollen, smooth, opake-white, marked with 

 distant violet zones ; umboes reddish-violet ; anterior 

 side obtuse, sUghtly concavely imjiressed, posterior 

 obtusely angled ; lunule indistinct, area rather large. 



Lamarck, Anim. sans vert. (Deshayes' edit.) vol.vi. p. 101. 



Hab. ? 



A species of very simple aspect, but well distinguished 

 by the chai'acters above noted. 



Species 53. (Mus. Cuming.) 



Mactra pura. Mact. testd ovato-trigond, depressiusculd, 

 crassd, solidd, aquilaterali, medio subgibbd, transver- 

 sim itKBqualiter obsolete striatd, candidissmd, sub epi- 

 dermide tenui Jlavescente, latere antico obtuso, postico 

 subangidato ; mnbonibus brembus, depressis ; lunula 

 subiiidistii/ctd, pUcato-striatd, ared coiwexd. 



The pure Mactra. SheU ovately triangular, rather de- 

 pressed, thick, solid, equilateral, rather gibbous in 



the middle, transversely unequally obsoletely striated, 

 very white, beneath a thin yellowish ejjidermis, an- 

 terior side obtuse, posterior slightly angulated ; um- 

 boes short, depressed; lunule rather indistinct, pli- 

 cately striated, area convex. 



Deshayes, Pro. Zool. Soc. 1831. 



Hab. Australia. 



A solid ivory-white shell, partially covered with a straw- 

 coloured fibrous epidermis. 



Species 54. (Mus. Cuming.) 



Mactra complanata. Mact. testd transversim trigond, 

 depressd, aquilaterali, securiforiid, laviyatd, alba, 

 utroque latere nequaliter obtusd, margine iiiferiore 

 acuto, regulariter arcuato ; lunula magna, elongato- 

 lanceolatd, sulco impresso circumdatd, in medio pro- 

 minente, ared elongatd, ovato-lanceolatd, imprmsd, 

 plana, angido duplici circumscripta ; umbonibus par- 

 vis, recurvis, imcinatis ; valvis tenuibus, intus candi- 

 dissimis ; lamina cardinali lata, temci ; dentibus late- 

 ralibus brevibus, lamellosis, triangularibus, abnpte. 

 truncatis ; sinu pallii brevi, semiellipticd, descendente. 



The smooth Mactra. SheU transversely triangular, 

 depressed, equUateral, hatchet-shaped, smooth, white, 

 equally obtuse on each side, lower margin sharp, re- 

 gularly arched ; lunule large, elongately lanceolate, 

 surrounded with an impressed groove, prominent in 

 middle, area elongated, ovately lanceolate, impressed, 

 flat, circumscribed by a double angle ; umboes small, 

 recurved, hooked ; valves thin, very white within ; 

 hinge lamina broad, thin ; lateral teeth short, laniel- 

 lous, triangular, abruptly truncated ; sinus of the 

 mantle short, semielliptic, descending. 



Deshayes, Pro. Zool. Soc. 1854. 



Hab. Indian Ocean. 



A singularly broad depressed species, with somewhat 

 of a Lucina aspect. 



Species 55. (Mus. Cuming.) 



Mactra semistriata. Mact. testd tran.sver.sim ovatd, 

 tumidd, gibbosd, subaquilaterali, lateribus rotundatis, 

 postico paulo longiore, livido-albd, nitente, ad umbones 

 purpurascente, epidermine tenui partim iiidntd, autice 



April, 1854. 



