MACTRA. 



Plate XXI. 



Species 119. (Mus. Cuming.) 



Mactra rostealis. Mad. testa transvt'raiiii. ovatd, pos- 

 tice compresso-rosiratd, alba, tenuissimd, pellncido- 

 vitred, mtbaquilateraU, latere antlco paiilo hremore, 

 concentrice undato-plicatd, et temmsitm ohliqne stri- 

 ata ; liinuld distinctd ; umbonibus parvis. 



The beaked Mactra. Shell transversely ovate, poste- 

 riorly compressly beaked, white, very thin, transpa- 

 rent, glassy, subequilateral, anterior side a little the 

 shorter, concentrically undulately plicated, very finely 

 obliquely striated ; lunule distinct ; umboes small. 



Deshayes, Pro. Zool. Soc. 1S54. 



Ilab. China Seas? 



A very thin transparent glassy shell, beaked on the 

 posterior side, which is the shorter, concentrically sculp- 

 tured with waved plaits converging over the posterior side, 

 as iu M. Thruciouh's. 



Species 120. (Mus. Cuming.) 



Mactra Senegalensis. Mad. testa transversim oblovgd, 

 compressd, iticeqailaterali, tenui, pellucido-vitred, con- 

 centrice nndato-plicatd et tenuissimi oblique striata, 

 latere antico rottmdato, postico lonijiore, cariiiato et 

 truucato ; mnbunibiis parvis. 



The Senegal Mactra. Shell transversely oblong, com- 

 pressed, inequilateral, thin, transparent, glassy, con- 

 centrically wave-plaited, and very finely obliquely 

 striated, anterior side rounded, posterior longer, keeled 

 and truncated ; umboes small. 



Philippi, Zeitschrift fur Malac. 1849, p. 27. 



Hab. Senegal. 



A thin glassy TIirncia-Y\\x, species, of which the poste- 

 rior end is finely keeled and truncated. 



Species 121. (Mus. Cuming.) 



Mactra plicatilis. Mad. testa transversim oblongd, 

 subangustd, medio compressd, subiequilaterali, tenui, 

 pellucido-vitred, epidermide fuscescente indutd, tmdato- 

 plicatd et subtilissime oblique striatd, latere antico ro- 

 tmidato, postico suMongiore, tenuicarinato et truncato; 

 umbonibus minutis. 



The plaited Mactra. SheD transversely oblong, rather 

 narrow, impressed in the middle, nearly equilateral, 



thin, transparent, glassy, covered with a brownish 

 epidermis, anterior side rounded, posterior rather 

 longer, wave-plaited and very finely obliquely stri- 

 ated, finely keeled and truncated; umboes very small. 



Deshayes, Pro. Zool. Soc. 1854. 



Hab. Philippines. 



Of a narrower transversely oblong form than the pre- 

 ceding species, but very similarly sculptured. 



Species 122. (Mus. Cuming.) 



Mactra canaliculata. Mad. testd ovatd, antice ob- 

 lique tumidd et gibbosd, postice compresso-rostratd, 

 paululum hiante, ineBquilaterali, latere antico multo 

 majore, tenui, Candida, epidermide stramined indutd, 

 concentrice irregularittr plicato-costatd, radiatiin pe- 

 culiariter tenui corrugato-siriatd ; luniild oblongo- 

 cordatd ; umbonibus parins, upproximatis. 



The channelled Mactra. Shell ovate, anteriorly ob- 

 liquely swollen and gibbous, posteriorly compressly 

 beaked, a little gaping, inequilateral, anterior side 

 much the larger, thin, white, covered with a straw- 

 coloiu'ed epidermis, concentrically irregularly pli- 

 cately ribbed, radiately pecidiarly finely wrinkle-stri- 

 ated ; lunule oblongo-cordate ; umboes small, close. 



Luiraria canaliculata, Say. 



Mactra Campecliensis, Gray in Wood Ind. Test. Supp. 



Hab. South Carolina. 



This fine shell is what might be termed a reversed shell, 

 the anterior side being the larger, swollen and obliquely 

 gibbous, while the posterior is smaller and compressly 

 beaked. 



Species 123. (Mus. Cuming.) 



Mactra Anatinoides. Mact. testd ovatd, inaquilaieraU, 

 antice oblique tumidd, postice breviter truncato, Jdante, 

 pellucido-albd, suhvitred, conceHlrice irregulariter stri- 

 ata et obscure plicatd, ad margines epidermide indutd. 



The Anatina-like Mactra. Shell ovate, inequilateral, 

 anteriorly obliquely swollen, posteriorly rather shortly 

 truncated, gaping, pellucid-white, rather glassy, con- 

 centrically irregularly striated and obscurely pHcated, 

 covered with an epidermis at the margins. 



Mactra tenera ? Deshayes (not of Gray in Wood Index 

 Test. Supp.). 



May, 1S54. 



