MACTEA.— Plate XVII. 



tundato, postico sulirostraio, longiore ; area lunuldqne 

 subampUs, striaiis ; ligamento extus conspicuo ; um- 

 botiibus approxhnatls. 



The subteuncate Mactra. Shell ovately subtriau- 

 gular, inequilateral, transversely striately grooved, 

 chalk-white beneath a dirty-yellowish epidermis, an- 

 terior side rounded, posterior slightly beaked, longer; 

 area and luuule rather large, striated ; ligament con- 

 spicuous without ; umboes approximated. 



Montagu, Testacea Britannica, p. 93, and Sup. p. 37- 

 pi. 37. f. 1. 



Triyonella subtruncata. Da Costa. 

 Mactra ladea, Poli. 

 Mactra trmicata. Brown. 

 Mactra deltoides, CoUard. 

 Spkula subtruncata. Gray. 



Hah. European Seas. 



A rather solid epidermis-covered shell, somewhat re- 

 sembling Gnathodon in general aspect. 



Species 91. (Mus. Cuming.) 



Mactra radiolata. Mact. testa trigond, obliqud, in- 

 aquilaterali, turgidd, cordiformi, sub epidentiide fla- 

 vescente tenuissimd atbd, rosea radiolata, latere antico 

 paiilo breviore, lati rotundato, postico rapide declivi, 

 attemiaio ; lunula aredque convexiusculis, regulariter 

 plicato-striatis ; umbonibus tumidis, prominentibus, pa- 

 rum obliquis. 



The finely-rayed Mactra. Shell triangular, oblique, 

 inequilateral, swollen, heart-shaped, white, finely 



rayed with rose beneath a very thin yellowish epi- 

 dermis, anterior side a little the shorter, broadly 

 rounded, posterior rapidly slanting, attenuated ; lii- 

 nule and area rather convex, regularly plicately stri- 

 ated ; uud)oes swollen, prominent, a little oblique. 



Deshayes, Pro. Zool. Soc. 1854. 



Hah. Island of Zebu, Philippines ; Cuming. 



Distinguished by its shortly triangular form, and deli- 

 cately red-rayed painting. 



Species D2. (Mus. Cuming.) 



Mactra Eeevesii. Mact. testa elongato-transversd, do- 

 naciformi, incequilaterali, compressd, alba, ad umbones 

 eleganter concentrice pUcatd, delude lavigatd, nitidd, 

 latere antico longiore subarcuato et rostrato, postico 

 oblique truncate, anyulatis, laterihus ambobus hiantihus ; 

 lunula impressd, lanceolato-ovatd, area magna, concavd, 

 utrinque carinatd. 



Eeeves's Mactra. Shell elongately transverse, donax- 

 shaped, inequilateral, compressed, white, concentri- 

 cally elegantly plaited about the umboes, then 

 smooth, shining, anterior side rather arched and 

 beaked, posterior obliquely truncated, angled, both 

 sides gaping ; lunule impressed, lanceolately ovate, 

 area rather large, concave, keeled on each side. 



Gray, Ann. and Mag. Nat. Hist. 1837, p. 373. 



Hah. Malacca. 



A very characteristic peculiarly oblong arched transverse 

 shell, of subtransparent substance, gaping at both ends. 



