1878.] FORMOSA AND THE PERSIAN GULF. 731 



aspect of the latter, namely the moulding of the edges of the upper 

 valve by the animal to the surface of the substance to which the 

 shell is attached, no doubt, was employed by the Oyster here figured ; 

 for I do not think that this alteration of outward appearance has 

 been in any way effected by contact of the tentacular cirri which 

 proceed from the edge of the mantle of the Trochus, because if this 

 were the case some alteration in colour would have been expected. 



The lower valve is white both externally and within, and, being 

 thin, does not conceal the granular surface of the Trochus upon 

 which it rests. The upper valve is olive-green within, and smooth, 

 with the exception of the pear-shaped muscular scar and a few 

 small granules scattered all round the margin. The exterior is dark 

 lilac, with six obscure brownish rays, most observable towards the 

 margin, and terminating at the digitations or prolongations at the 

 edge. 



The lamellated surface, so common to the upper valves of most 

 Oysters, is almost altogether obliterated, and only here and there 

 traces of it are noticeable. The exterior is rather smooth, sub- 

 angular, the indistinct granules arranged in series corresponding to 

 those on the Trochus ; and the suture dividing the last and the pen- 

 ultimate whorls, and a depression or sulcus round the middle of the 

 former, are also reproduced. The specimen is in the collection of 

 Mr. Carl Bock. 



CyprjEA peasei, Sowerby. (Plate XLVI. figs. 13 & 14.) 



Cyprcea peasei, Sowerby, Thesaurus Conchyl. iv. pi. 311. figs. 

 167, 168. 



Hab. Mauritius. Coll. Carl Bock. 



The shell here figured appears to be a monstrous growth of this 

 species. The alteration of form and the obtuse ridges on the dorsal 

 surface are suggestive of certain forms of the genus Ovulum. 



CONUS PASTINACA. 



Much uncertainty and confusion exists with regard to the deter- 

 mination of this Lamarckian species. The original description of it 

 is so brief that it is absolutely impossible ever to know with cer- 

 tainty what species Lamarck really had before him, more especially 

 as the actual type (which has been lost) was never figured by him, 

 nor does he refer to any previously published figure. The shell de- 

 scribed and delineated by Kiener (Coq. Viv. pi. 26. fig. 2) certainly 

 cannot be the true C. pastinaca. The species there represented 

 (unknown to me) is decidedly distinct. The character of the spire 

 does not at all agree with Lamarck's description, which is as fol- 

 lows : — "spira obtusa, immaculata, submucronata ;" and again in 

 French: "aspirenon tachee." Kiener's shell has a rather con- 

 cavely elevated spire and fulvous blotches upon it. 



Reeve's idea of C. pastinaca, figured (Conchol. Icon. i. pi. 46. 

 fig. 257, copied by Sowerby, Thesaurus Conchyliorum, hi. pi. 201. 

 fig. 353) from a specimen in the British Museum, is also an erro- 

 neous one. This shell I have very carefully examined, and unhesi- 



