S T \l M A. 



Species 81. (Mus. Barclay.) 



OsTU.EA NOBiLis. Ost. testd magttd, ponderosd, com- 

 pressd, discoided, subcequilaterali, suborbicutari, 

 siipeme expansd, prope umhones albidd, infrd ufqiic 

 admarginem cinereo-purpureA, plicis viagnis divari- 

 catis Icevigatis, snbjbi-nicatis radiatd ; valvd in- 

 feriori ad marginem superiorem svperanti, foliaceo 

 margine subccendeo, angulalimundato. Marginc 

 dorsali utriusqiie valvce ad latcra, prope cardinem 

 recti striata. 



The noble Ostu^a. Shell largo, pomlerous, com- 

 pressed, discoidal, subequilateral, suborbicular, 

 expanded above, whitish near the uniboes, thence 

 to the margin ashy-purple, rayed with lixrge 

 diverging, somewhat vaulted smooth plaits ; 

 lower valve exceeding the upper at the margin, 

 foliaceous, margin bluish, angularly waved; dorsal 

 margin of each valve near the binge at the sides, 

 straightly striated. 



SOWERBY. 



Hah. Barclay Island, Mauritius. 



Another of the rare products of the above wonderiiil 

 little islet 



Species iS^. (Mtis. Barclay.) 



OsTij.F.A iN-.wjL-iVAi.vis. OxI . ti'sld irvcijuluri, mb- 

 solidd, rugnsd, valilu iiurqiiihilfrnli, sublrigond, 

 cxtus sordide albd, iiit!'.< /Dirpurco maculato, ad 

 margines strigato, valnl iiij'rriori ad marginem 

 superiorem superanti, temdler expansd et extanti, 

 e.vtus subcostatd, cardine trigono, producto ; 

 cicatrice laterali, nigrescenti vel castaned ; ralvd 

 sxiperiori cmnpressd, sttbplanulatd. 



The inequivalve OsTKiEA. Shell irregular, rather 

 solid, rough, very inequilateral, subtrigonal, out- 

 wardly dirty white, within spotted with purple 

 and striped at the margin, lower valve extending 

 beyond the upper, thinly expanded and standing 

 up, externally slightly ribbed; hinge trigonal, 

 produced; scar lateral, blackish or chestnut; 

 upper valve compressed, a little flattened. 



Sowerbt. 



Ifab. Madagascar. Mauritius. 



The specimen with the lighter internal colour is 

 from Madagascar. The darker one is from the Mauri- 

 tius. In the two specimens the apex turns in opposite 



November, lb71. 



