S T 11 /E A. 



Plati: XXIII. 



Sjiecies :,?,. (Fig. a, l>, ^[lls. Taylor.) 



Osrn-EA BiCOLOiv. Ost. tedA ocato-suhtrujottil , soliili), 

 compressd, albidd, purpurea latissimi biradiatd, 

 vix lamellosd, margine simplici, nonnunquani un- 

 dulato ; umhonibus acyiiminatis : valvulls intuis 

 alhis, marginihus lateralibus Iccvigatis. 

 The two-coloui!EI) Ostr^.v. Shell ovate-subtrigonal, 

 solid, compressed, whitish, with two very broad 

 purj)le rays, scarcely lamellar, margin simple, 

 sometimes undulated, umboes acuminated ; valves 

 white within, the lateral margins smooth. 

 Hanley. Conchological Miscellany. Ost. fig. 2. 

 Hab. Senegal (?). 



The original specimen described by Mr. Ilauley 

 was attached by its entire surface to the bottom of a 

 ship. One of Mr. Taylor's specimens has portions of 

 wood adhering to it, which have been pierced by speci- 

 mens of a Teredo. 



Species 54. (Mus. Hanley.) 

 OsTR.EA LAMELLOSA. Ost. tcsld utrdquc valvA valdc 

 foliaced et squamiferd, albidd, purpurea leviter 

 variegatd, ovaid, crassd ; valcd superiori subde- 

 pressd, versus umbonem Iceviv^culd, concentrice 

 strigald squamis purpureis, extantibus laminatd ; 

 valvd inferiori profuride excavatd, laminibus ex- 

 tantibus lobatis ornatd. 

 The LAMELLAR OsTR^EA. Shell very foliaceous and 

 squamil'erous in both valves, whitish, slightly 

 variegated with purple, ovate, thick ; upper valve 

 subdepressed, rather smooth and concentrically 

 striped towards the umbo, laminated with purple 

 outstanding scales ; lower valve deeply excavated, 

 ornamented with outstanding lobed lamina;. 



Biioccui, as in Philippi. Moll. Sic. 

 Ilab. Lake Fusaro, near Naples. 



It may bo considered an open question whether this 

 form, like Ostnra Cyruusii, should be regarded as a 

 distinct species, or merely a variety of Ostrcea edulis. 

 The specimen in Mr. Hanley 's collection was identified 

 by Philippi himself. 



Species 55. (I\Ius. Hanley.) 

 O.STi;.EA DKiMiESSA. Ost. testd suborbicidariter svhtri- 

 gond, complanatd, deprensd, nlbida, radiis tribun 



SlljH 



viht 



jmrpvi-iis hills iiirl,} : valciih'i 

 concfiitrici.'i ,-.</ii(i nninnii iiidlit,} 

 laceratis, ,l<riiiiilii'iitihiis : iuii/>oiiiliii^ p<iri:'is : mar- 

 gine domali ulrinque declivi. 

 The depressed O.str^a. Shell suborbicularly sub- 

 trigonal, llattened, depressed, whitish, painted 

 with three broad purple rays ; upper valve 

 covered with layers of scales ; scales smootli, 

 lacerated, decumbent; umboes small, dorsal mar- 

 gin sloped on each side. 

 Philiiti. MoUusca SiciUa;. 

 Ilab. Adriatic. 



This is usually regarded as a form of Ostrwci t 

 assuming a flattened orbicular form on account i 

 Hat surface to which the shell is attached. 

 ai>pearance of this specimen is, however, remarkable 

 for the broad purple rays, which are not seen in 

 Ostrma edulis., except in very yoimg specimens, such as 

 represented in our Plate v. fig. 8 d. Andin that case 

 there are not, as here, three distinct rays with broad 

 intervals, but the young shell is nearly covered with 

 purple divided by a light ray in the centre. Ostrcea 

 depressa may possibly be a species hereditarily dis- 

 tinct. 



'.dulis, 



af the 



The 



September, 1871. 



