S T R .E A. 



Species 22. (Fig. a, Mus. Brit. Fig. b, c, Sowerby.) 



()sTR«A CRiSTA-GALLi. Ost. testd plerumque subqua- 

 dratd, valklissime plicatd, plicis angulatis profun- 

 dis, divaricatim granoso-striatd jmrpweo-fuscA 

 vel fulvA vel albidd, versiis marginem pallide 

 violaced ; iniils pallidiori, ad marginem granu- 

 hiid ; cardine lato, complanalo ; valvuld inferiori 

 per lobis foliaceis productis ad niadreporas mpes- 

 que adhmrenti. 



The cock's-comb OsTr.^.\. Shell generally subqua- 

 drate, strongly plicated, folds angular and deep, 

 divergently granularly striated, purple brown, or 

 fulvous, or whitish, pale violet towards the 

 margin ; paler within, granulated at the margin ; 

 hinge wide, flattened ; lower valve adhering to 

 madrepores and rocks by produced leafy lobes. 



LinnjEus (Mytilus) Systema Naturaj. 



Hah. Indian Ocean. 



Oysters of this species occur in fine groups, attached 



to each other by a portion of their surface, and to 

 madrepores by lobelike projections. 



Species 23. (Mus. Cuming in Brit.) 



OsTR^A viitESCENS. Ost. tesld suboibiculari, solidd, 

 intits viridi ; valvuld inferiori profwndd, margine 

 laqueato ; valvidd superiori planulatd, divaricatim 

 costatd, costis crebris, rotundis, crassis lineis rube- 

 scentibus notatis ; cardine lato, medio excavato. 



The virescent Ostr^ea. Shell suborbicular, solid, green, 

 within ; lower valve deep with fluted margin ; 

 upper valve flattened, divergently ribbed, ribs 

 close, rounded, thick, marked with reddish lines ; 

 hinge wide, excavated in the middle. 



Angas. Proc. Zool. Soc., 1868. 



Uab. Port Jackson, Australia. 



In some respects resembling Ostrcea pyxidata, but 

 the ribs are thick and close tosrether. 



January, 1871. 



