MACTRA. 



Plate VI. 



Species 21. (Mus. Cviming.) 



Mactea tumida. Mact. testa ovalo-trigond, ventricosis- 

 simd, tumidd, tenuiculd, irregidariter transversim stri- 

 ata, versus umbones lavigatd, exiremitatibus angulatd, 

 antice subobtusd, albo-Jiavescente, ad umbones violaceis ; 

 mnbonibus cordatis, subapproximatis ; siiiu pallii brevi, 

 lato, oblique ascendeute. 



The swollen Mactea. Shell ovately triangular, ex- 

 tremely ventricose, swollen, rather thin, irregularly 

 transversely striated, smooth towards the umboes, 

 angled at the extremities, anteriorly a little obtuse, 

 whitish-yellow, violet at the umboes ; umboes heart- 

 shaped, rather approximated ; sinus of the mantle 

 short, broad, obliquely ascending. 



Chemnitz, Conch. Cab. vol. vi. p. 218. pi. 21. f. 210- 

 212. 

 Mactra turgida, Gmelin. 



Hab. Island of St. Thomas, West Indies ; Cuming. 



A plain smooth largely swollen species, of a whitish- 

 yellow cast, tinged at the umboes with violet. 



Species 22. (Mus. Cuming). 



Mactea antiqdata. Mact. testa trigond, injtatd, solidi- 

 usculd, aquilaterali, exiremitatibus subattenuatd, trans- 

 versim dense teuuissivie striata, pallide spadiced, subti- 

 liter albiradiatd, ad timbones intense violaced ; lunula 

 aredque subgrandibus, eleganter plicato-striatis, iittus 

 violascente ; sinu pallii lato, rotuiidaio. 



The ancient Mactea. Shell triangular, inflated, rather 

 soKd, equilateral, subattenuated at the extremities, 

 transversely densely very finely striated, light fawn- 

 colour, finely white-rayed, deep violet at the umboes; 

 lunule and area rather large, elegantly pbcately stri- 

 ated, interior violet ; sinus of the mantle broad, 

 rounded. 



Spenglee, Skriv. Naturch. Selsk. vol. v. part 2. p. 102. 

 Mactra violacea australis, Chemnitz. 

 Mactra Chenmitzii, Gray. i 



Hab. Bay of Manilla ; Cuming. 



A more compressed and solid species than the preced- 

 ing, faintly white-rayed, with very deep-stained violet um- 

 boes. 



Species 23. (Mus. Cuming.) 



Mactra Largillierti. Mact. testa ovato-trigond, sub- 

 aquilaterali, tumidd, postice Idante, sub epidermide ni- 

 tente, oUvaceo-flavd, radiis angustis violaceis pictd; 

 area lunuldque planiusculis, eleganter plicato-striatis ; 

 ligamento externa valde conspicuo, lamina ab interno 



Laegilliert's Mactra. Shell ovately triangular, nearly 

 equilateral, swollen, posteriorly gaping, olive-yellow, 

 painted with narrow violet rays beneath a shining 

 epidermis ; area and lunule rather flat, elegantly pli- 

 cately striated ; outer ligament very conspicuous, 

 divided by an internal lamina. 



Philippi, Zeitschi-ift fiir Malac. 1848, p. 162. Abbild. 

 und Besch. Couch, vol. ii. p. 135. pi. 3. f. 1. 



Hab. Gaboon, West Africa. 



Of a peculiar swollen transverse form, covered with a 

 shining yellow epidermis. 



Species 24. (Mus. Cuming.) 



Mactea Chmingii. Mact. testa ovato-trigond, tenui, 

 ventricosissimd, cordiformi, subcequilaterali, transversim 

 irregidariter obsolete striata, cuticuld tenui fiavescente 

 fibrosa pellucidd indutd, albd, incarnato-roseo distanter 

 radiatd, latere antico rotundato, postico pecuUariter 

 compresso-rostrato ; mnbonibus tumidis, cordatis, sub- 

 nppro.nmatis ; lunidd latiuscidd, ared angustd, elon- 

 gatd ; sinu pallii lato, brevi^simo. 



Cuming's Mactea. Shell ovately triangular, thin, very 

 ventricose, heart-shaped, nearly equilateral, trans- 

 versely irregularly obsoletely striated, covered with 

 a thin yellowish fibrous pellucid cuticle, white, dis- 

 tantly rayed with flesh-rose, anterior side rounded, 

 posterior peculiarly eompressly beaked ; umboes 

 swollen, cordate, rather approximated ; lunule rather 

 broad, area narrow, elongated ; sinus of the mantle 

 broad, very short. 



Deshayes, Pro. Zool. Soe. 1854. 



Hub. Moluccas. 



An exquisitely delicate and characteristic species, light 

 and ventricose, eompressly beaked on the posterior side, 

 ivory-white, marked with faint distant flesh-rose rays, and 

 covered with a peculiar linear silky fibrous epidermis. 



April, 1854. 



