S T R iE A. 



Species 34. (Mus. Brit.) 



OsTR^A CUCULLATA. Ost. testd subtrigmiA solidisdmd, 

 pUccUd, plicis angtdaribus, pJenunqve magnis prope 

 apicem cdbidd, versits itiarginem purpured fasciis 

 den»ioribus strigatd ; vahnild inferiori crassd, al- 

 teram ad marginem, giiperanti, sublus margmem 

 cardinalem cucidlafd cardine elongato, frequenter ad 

 umbonem valde prodnctd, plicis elcmgatis, nonnun- 

 quam rotundatis et imbricalis ; valvuld superiori 

 medio planulatd versus marginem piicatd. 



The hooded O.str^a. Shell subtrigonal, very solid, 

 plaited, plaits angiilar, generally large, whitish 

 near the apex, jnirple toward.s the margin, striped 

 with deeper bands; lower valve thick, overlapping 

 the other at the margin, hooded under the hinge 

 margin, hinge elongated, frequently nuich pro- 

 duced at the apex; plaits elongated, sometimes 

 rounded and imbricated ; upper valve fiat in the 

 middle, plaited towards the margin. 



Born. Mus. Ind. Cses. Tab. G, f. 11, 12. 



Osticea cornucopia. Chemnitz, f. 679. 



Ostrcea Forskali. Chemnitz, f. 671 bis 6. 



Considering the great variation observable in this 

 species, particularly in the elongation of the hinge, I 

 think Mr. Hanley right in referring to it the Ostnea 

 comucopiw and the Ostrcea Forshali of Chemnitz. The 

 latter is represented by our fig. a, from a specimen in 

 the collection of the British Museum, which has the 



hinge elongated to an enormous extent, the result of 

 the specimen having been attached only by a small part 

 of its surface. 



Species 35. (Mus. Sowerby.) 

 Ostr.«;a Mexicana. Ost. testd ad lapides adhcerenti, 

 ovatd, tenui, subcompressd, ad marginem laxe pii- 

 catd ; valvuld inferiori cos'atd, haud profunda, 

 albidd, purpurea pictd, alteram ad marginem su- 

 peranti ; valvuld superiori medio convexo, versus 

 marginem plicate, albido, velfulvo, lineis strigisque 

 fuscis vel purpureis, et versiis apicem fascid mediand 

 siibpurpured, fasciis albis duabus marginald, 

 rudlatd ; apicibus incurvis, cardine tenui, angusto. 

 The Me.xican OstrjEa. Shell adhering to pebbles, 

 ovate, thin, subcompressed, loosely plaited at the 

 margin ; lower valve ribbed, not deep, whitish, 

 painted with purple, overlapping the other ; upper 

 valve convex in the middle, plaited towards the 

 margin, whitish, or fulvous, rayed with brown or 

 purple lines and stripes, and towards the apex a 

 central purplish band edged with two white bands; 

 apices curved inwards ; hinge thin, narrow. 

 Sowerby. 

 Hab. Tehuantepec, Mexico. 



A rather variable shell, having some relations with 

 the preceding. It is a much thinner shell, witli no 

 tendency to a trigonal form, to a prolongation of the 

 hinge, or to any depth of hollow under the hinge. 



February, 1871. 



