S T R vE A. 



Species 28. (Miis. Brit.) 



OsTK^A SOLIDA. Ost. testd crai>!!d, ohlongo-suhovatd, 

 swprh subaUe7iuatd, versus marginem venirahm 

 expansd, plicis numerosis, suhrotundif, radiantibus 

 laqueatd ; valvuld inffriori hand profunda, cras- 

 sissimd, intiis medio juseo nigricanti s^tbulatd turn 

 subaureo-fuscd, margine ventrali /usco-piirjmred : 

 marginibiislateralibuscrenulatis;marginecardinali 

 angusto, subelongato, complanato ; valvuld snpe- 

 riori irregulariter tiiberculald, alhidii, puUtdissinie 

 purpurea svhulald. 



The solid Osth^a. Shell thick, oblong-subovate, rather 

 attenuated above, expanded towards the ventral 

 margin, fluted with numerous rounded radiating 

 ribs; lower valve not deep, very thick, clouded 

 within by blackish brown in the centre, then golden 

 brown, ventral margin pvirplish brown, lateral 

 margins crenulated ; hinge margin narrow, rather 

 long, flattened ; upper valve irregularly tuber- 

 culated, whitish, very lightly clouded with purple. 



SOWERBT. 



Hob. Gulf of Panama. 



There is a second specimen in the British Museum col- 

 lection, which is straighter, and less distinctly wrinkled 

 than the one figured, with considerably less colour 

 within. 



Species 20. (Mus. Brit.) 



OSTR.EA TURBiN.\TA. Ost. testd fuscd, muximd, crassd 

 medio complanatd, versiis marginem plicis paucis, 

 maximis, acute angulatis, armatd; valwJd infer iori 

 crassissimd. ad marginem alteram jyaiilo superanti; 

 intiis medio albidd, limbo deme fmcato, ma/rgine 

 cardinali elongato, angusto; valmdd superior!, 

 medio albido, planulato, impressione musculari 



The turbinated Ostr^a. Shell brown, very large, 

 thick, flattened in the middle, armed towards the 

 border with few very large acutely angular plaits ; 

 lower valve very thick, a little exceeding the other 

 at the margin ; within whitish in the middle, deep 

 brown at the border, hinge margin elongated, 

 narrow ; upper valve whitish in the middle, flat- 

 tened ; muscular impression very large. 



Lamarck. Animaux sans vertebres. Ostrsce, No. 44. 

 HaJj. ? 



No locality is assigned to the specimen in the British 

 Museum of this large oyster, which differs from Ostrwa 

 Sinensis chiefly in the magnitude and angularity of 

 the plaits. 



February, 1871. 



