M A C T R A . 



Plate X. 



Species 37. (Mus. Cuming.) 



Mactra cyprinus. Maet. testa ovato-trmisversd, <equi- 

 laterali, teuid, fragili, alba, diaplmnd, traversim stri- 

 ata, ad umboues (jibbd, avtice decl'wi et obtmd, postice 

 dilatatd, siMruiicatd, valde hiante, Ihied promiuente 

 oblique dectirrente, latere antico piano, postico prom.i- 

 nente, aperto. 



The caep Mactka. Shell ovately transverse, equilateral, 

 thin, fragile, white, diaphanous, transversely striated, 

 gibbous at the umboes, anteriorly slanting and ob- 

 tuse, posteriorly dilated, subtruncated, very much 

 gaping, with a prominent line running down ob- 

 liquely, anterior side flat, posterior prominent and 

 open. 



Gray, Wood, Index Test. pi. 1 . f. 1 . 

 Lutraria ci/priiw. Gray. 

 Oyprieia cyprina, Gray. 



Hub. ? 



An interesting semitransparent fragile species, having 

 somewhat the aspect of AnatiiM. 



Species 38. (Mus. Cuming.) 



Mactra caeinulata. Mact. testa trigono-transversd, 

 tumidd, (squilaterali, utriiique acute angulatd, tenuis- 

 sime striata, albd, epidennide tenui fulvd iiidutd ; lu- 

 nula aredque indistinctis, grandibus, medio subelevatis; 

 umbonibus augulatis ; sinu pallii angusto, profundo, 

 oblique ascendente. 



The finely-keeled Mactra. Shell triangularly trans- 

 verse, swollen, equilateral, sharply angled on both 

 sides, veiy finely striated, white, covered with a thin 

 frdvous epidermis ; lunule and area indistinct, large, 

 slightly raised in the middle ; umboes angled ; sinus 

 of the mantle narrow, deep, obliquely ascending. 



Deshayes, Pro. Zool. Soc. 1854. 



Hab. Gulf of California. 



A shell of comparatively small size and of light growth, 

 partaking of the typical characters of M. Bonaciformis, 

 and from the same locality. 



Species 3!). (Mus. Cuming.) 



Mactra polita. Mad. testd trigouo-ovatd, subaquila- 

 terali, solidd, cinereo-fuscescente, incariiato tiiictd. 



promisme fasciatd, dense striata, latere antico rotun- 

 dato, postico subfiexuoso-anguluto ; urubouibus minimis, 

 violaceis ; lunuld indistinctd, area magnd, medio snb- 

 elevatd. 



The polished Mactra. Shell triangularly ovate, nearly 

 equilateral, solid, light ash-brown, flesh-stained, pro- 

 miscuously banded, densely striated, anterior side 

 rounded, posterior slightly flexuously angled; um- 

 boes very small, violet ; lunule indistinct, area large, 

 slightly raised in the middle. 



Chemnitz, Conch. Cab. vol. vi. p. 222. pi. 22. f. 216, 217. 

 Mactra glabrata, Schroeter. 

 Mactra australis, Lamarck. 



Hab. Swan River. 



Thick-set with shining stria;, and of a light ash-colour, 

 promiscuously banded, with the umboes violet-tipped. 



Species 40. (Mus. Brit.) 



Mactra Spengleri. Mact. testd triangulori, transversa, 

 (Bquilaterali, cuneiformi, transversim obsolete striatd, 

 a.lbo-lntesceute, sub epidermide squalide fusculd; um- 

 bonibus minimis, distautissimis, fosstdd ligamenti tri- 

 angulari, exterius apertd, separatis; lunula magna, 

 convexiusculd ; latere postico piano, lata, ai/gu.Hd, 

 acutd, circum-scriptd ; valvis solidiusculis, iutus albi^; 

 dentibus lateralibus brevibus, cardiue approximatis ; 

 sinu pallii profundo, obtuso, horizontali. 



Spengler's Mactra. Shell triangular, transverse, equi- 

 lateral, wedge-shaped, transversely obsoletely striated, 

 whitish-yellow, beneath a dirty light brown epider- 

 mis; umboes very small, very distant, separated by 

 a ligamentai-y pit which is triangular, and outwardly 

 open ; lunule large, rather convex, posterior side flat, 

 broad, narrow, sharp, circumscribed; valves rather 

 solid, white within; lateral teeth short, approxima- 

 ting to the hinge ; sinus of the mantle deep, obtuse, 

 horizontal. 



Linn^ds, Syst. Nat. (12th edit.) p. 1125. 

 Schizodesma Spengleri, Gray. 



Hab. Cape of Good Hope. 



Remarkably distinguished from aU other species by its 

 sharp wedge-like form, and by its outwardly seen exca- 

 vated crescent-like ligament pit. 



Api-il, 1854. 



