S T R M A. 



Species y. (Fig. a, b, c, Mus. Brit.) 



OsTn^A ROSTrrATA. Ost. testd elongato-sukriffond, valde 

 foliaced, plermnque arcuatd, albidd ; valvuld mpe- 

 rioii breviusndd, compregsd, inferiori crassd, ex- 

 cavatd ; cardine ekmgato, in rah-uld inferiori medio 

 profundi excavato, mpei-inri medio tmmdo; im- 

 pressione musculuri utnh/iir valvuld phrumque attc- 

 nuatd, castaned. 



The rostrated Cstk^a. Shell elongate-subtrigonal, 

 very foliaceous, generally arched, whitish ; upper 

 valve rather short compressed, lower thick, exca- 

 vated, hinge elongated, in the lower valve deeply 

 excavated in the middle, in the upper tumid in 

 the middle; muscular impression in each valve 

 generally attenuated, chestnut. 



CiiEMN-iTZ. Conch. 8. t. 73. f. 677. "0. rostrata, 

 parva et maxima.'" 



Oiftiwa Virginiana, Gmelin. 

 Ostrcea Virgintca, Lamarck. 

 Ostrcea Canadensis, Lamarck. 

 Ostrwa hm-ealis, Lamarck. 

 Hah. New York. Virginia. Canada. 



The shell of early growth represented at fig. e, being 

 attached by a small part of its surface to a smooth 

 substance has a form very similar to our edible oy.ster. 

 The elongated laterally compressed boat form, fig. a, b, 

 represents 0. Virginica, Lamarck. We have not 

 thought it necessary to give a figure of the form 

 Canadensis, Lamarck, which is shorter, more curved, 

 and thicker, very foliaceous in the lower valve. In 

 the Virginica form, the attenuated beak with central 

 ridge, and groove and side ridges, presents a curious 

 feature. The largest specimen in the British Museum 

 is more than a foot long. 



January, 1.S71. 



