MACTRA. 



Plate XI. 



Species 44. (Miis. Cuming.) 



M.\CTRA VITREA. Mad. testd trigond, turgidnld, teiinis- 

 simd, vitreo-albd, iruequilateraU, idrinque hiante, la- 

 tere antico brevi, iubcompremi, lira obsoletd descen- 

 deiite, po-stico producto, rotundato, eleganier corrngato- 

 plicuto ; umhonibus augulxdh, nitidi pUcato-striatis ; 

 luniild vix nulld, medio elevatd, area subampld, cordi- 

 foriiii, jilano-excavatd. 



The glassy Mac tea. Shell triangular, rather swollen, 

 very thin, diaphanous, glassy-white, inequilateral, 

 gaping at both ends, anterior side short, rather com- 

 pressed, with au obsolete ridge descending, posterior 

 produced, rounded, elegantly wrinkle -plaited; um- 

 boes angled, neatly plicately striated ; lunula scarcely 

 any, raised in the middle, area rather large, heart- 

 shaped, flatly excavated. 



Gray, Ann. and Mag. Nat. Hist. 1837, p. 372. 



ITab. Moluccas. 



A delicate pellucid white shell, elegantly wrinkle-plaited 

 down the posterior side. 



Fig. 45. (Mus. Cuming.) 



The shell here figured represents the Mactra Igpiciis, 

 Gray, which proves to be a variety of M. ediilis. 



Species 46. (Mus. Cuming.) 



Mactra nitida. Mact. testa ovato-trigond, eeqiiilatei'ali, 

 turgidnld, antice obtiisd, podice mbangulatd, latere 

 postieo depresso, angiilo acutiuaculo circumscripto, 

 caudidissimd, nitente, sub epidermide Jlavicante, pos- 

 tice sqtialidiore ; mnbonibus parvis ; lumdd magna, 

 eleganter sulcata, ovali, fossidd ligamenti exterius 

 apertd ; valvis intus albis ; sinii pallii brevi, trigono. 



The suining Mactra. Shell ovately triangular, equi- 

 lateral, rather swollen, obtuse anteriorly, slightly an- 

 gled posteriorly, posterior side depressed, circum- 

 scribed into a rather sharp angle, very white, shin- 

 ing, beneath a yellowish epidermis, duller on the 

 posterior side ; umboes small ; lunule large, ele- 

 gantly grooved, oval, ligamentary pit outwardly open ; 

 valves wliite within ; sinus of the mantle short, trian- 

 gular. 



Mactra iiitida, Schroeter, Einl. Couch, vol. iii. pi. 8. f. 2. 



Mactra straminea, Lamarck. 

 Sc]d:odes»ia nitida. Gray. 

 Hab. Senegal. 



Of a shining white substance, covered with a thin shin- 

 ing horny epidermis, and peculiarly sharply angled down 

 the posterior side. 



Species 47. (Mus. Cuming.) 



BIactra fragilis. Mact. testa ovato-obloiigd, subaqui- 

 laterali, compressd, transversim tenue et irregulariter 

 striata, alba, sub epidermide fibrosa griseo-flavescente, 

 in latere postieo nigricante, latere antico obtuso, pau- 

 lulum attenuato, postieo subtruncato, hiante, bilirato, 

 Uris subdistantibus ; umbonibus compressis, approxi- 

 maiis ; lunula aredque elongatis, angustis. 



The fragile Mactra. Shell ovately oblong, nearly 

 equilateral, compressed, transversely finely and irre- 

 gularly striated, white, beneath a greyish-yellow 

 fibrous epidermis, blackish on the posterior side, an- 

 terior side obtuse, a little attenuated, posterior sub- 

 truncated, gaping, two-ridged, ridges rather distant ; 

 umboes compressed, approximated ; lunule and area 

 elongated, narrow. 



Chemnitz, Conch. Cab. vol. vi. p. 336. pi. 24. f. 235. 

 Mactra Brasiliaua, Lamarck. 

 Mactra oblonga. Say. 

 Spisula fragilis, Gray. 



Hab. Honduras ; Dyson. 



Of rather slight form, characterized by a space down 

 the posterior side between two ridges, in which the epi- 

 dermis is darker than on the rest of the shell. 



Species 48. (Mus. Cuming.) 



Mactra semisulcata. Alact. testa transversim ovatd, 

 imnidd, soUdiusculd, incequilaterali, albidd, uitente, 

 epidermide tenia straminea partim indutd, latere an- 

 tico rotundato, transversim sulcato, sulcis medium ver- 

 sus evanidis, postieo conspicuii rostrato ; lunula ared- 

 que latiusculis, plicato-striatis ; umbonibus tumidis, 

 politis, approxiiuatis. 



The half-grooved Mactra. Shell transversely ovate, 

 swollen, rather solid, inequilateral, whitish, shining, 

 partially covered with a thin straw-coloured epider- 



April, 1854. 



