S T R vE A. 



species 18. (Mus. Sowerby.) 



OsTR^A PERMOLLis. Ost. testd qwiilrato-suhtrigond, 

 cotnprefsd, subcequivalvi, inlus subaured vel albd- 

 ccerulescente, ad latera leevigatd, margine submridi, 

 cardine producio, angusto, acnminato ; valvvld 

 inferiori purpurea suffusd, Icevir/atd ; valvuld 

 superiori paulo convexd epidermide permolli sub- 

 aureo-fusco indutd, prope mai-ginem ventralem 

 Iceviter squamosd. 



The soft Ostr^a. Shell quadr.ite-subtrigonal, com- 

 pressed, subfequivalve, slightly golden-tinted or 

 bluish-white within, smooth at the sides, greenish 

 at the borders, hinge produced, narrow, acumi- 

 nate ; lower valve suffused purple, smooth ; upper 

 valve a little convex, covered with a very soft 

 slightly golden-tinted brown, a little sijuamose 

 near the ventral margin. 



Sowerby. 



Hab. ? 



There is a kind of velvety softness in the outer 



covering of the upper valve in this shell which se-oms 



to distinguish it. 



Species 19. (Mus. Brit.) 



CsTRiEA OCHRACEA. Ost. irregulariter elongato-siibtri- 

 gond, inmquivalvi, solidmsculA hwigald, ochraced, 

 albo, purpurea, etfusco slrigatd aid variegaid, in- 

 tus ad marginem pU7pureo ; valndd inferiori pro- 

 fundd, superiorem superanti, cardine acuminatim 

 producio ; valvuld superiori sub-planvlatd. 



The ochraceous Ostr.e.\. Shell irregularly elongate- 

 sub trigonal, inffiquivalve, rather solid, smooth, 

 ochraceous, striped and variegated with white, 

 purple, and brown ; lower valve deep, overlapping 

 the upper, hinge produced in a point; upper 

 valve rather flattened. 



Sowerbt. 



Hab. Mazatlan. 



Some Sfiecimens of this are in the Mazatlan collec- 

 tion of the Britisli Museum, assigned by M. Carpenter 

 to the American species 0. virginiana, included in 

 this monograph among the varieties of 0. rostraia, 

 Chemn., with which, however, it is not easy to connect 

 the present species. 



Species 20. (Mus. Brit.) 



OsTR.«A rostralis. Ost. testd elongatd, irregulariter 

 undatd, laxe foUaced, albidd, purpurea fuscoque 

 slrigatd et variegatd, incequivalvi ; cardine acu- 

 minata, angusto, producio; valvuld inferiori intus 

 albd, ad margines superiares superanti. 



The beaked OsxRiEA. Shell elongated, irregularly 

 undated, loosely foliated, whitish, striped and 

 variegated with brown and purple, inajquivalve : 

 hinge acuminated; narrow, produced ; lower valve 

 white within, overlapping the upper at the mar- 

 gins. 



Lamarck. Anim. s. vert. Ostr»a, No. 13. 



Hab. River Tagus near Lisbon. Sir C. Trevelyan. 



In the label with this specimen at the Britisli Museum. 

 0. longirostris, Lam. (No. 17 in the Especes fossiles), 

 is referred to by Sir C. Trevelyan ; but as that species 

 is described as having in the lower valve a beak larger 

 than all the rest of the valve, the identification is con- 

 tradicted. 



Species 21. (Mus. Cum. in Brit.) 



OsTR^A Talienwahnensis. Ost. testd elongatd, tri- 

 gond, albd, purpurea fuscoque slrigatd et maculatd ; 

 perfoliaced; valvuld inferiori coniiexiusculd ; 

 foliaced, IcBviter plicatd, cardine producio attenuaJLo. 

 acuminata; valvuld superiori concentrice lami- 

 natd, laminis laqueatis, versus marginem ventralem 

 valide plicatd, expansd. 



The Talienwah Ostr^a. Shell elongated, trigonal, 

 white, spotted and striped with purple and white, 

 very foliaceous ; lower valve rather convex, folia- 

 ceous, slightly plicated, hinge produced, attenuated, 

 acuminated ; upper valve concentrically laminated, 

 the lamina; fluted, towards the ventral margin 

 strongly plicated, expanded. 



Crosse. Journal de Conchyliolagie. 



Ilah. Talienwah. 



This beautiful oyster is remarkable for its concentric- 

 fluted frills, and for the richness of the purple strijies 

 and spots set off by their white surface. 



January, 1871. 



