1891.] MR. E. A. SMITH ON SHELLS FROM ADEN. 433 



Bruguiere (Encycl. Meth. pi. 311. f. 5), and Bouanni (Mus. Kirch, 

 ii. pi. xvii. f. 129). The last-mentioned figure was described by 

 Gmelin under the name of Cardinm amboinense (Syst. Nat. p. 3255). 

 The specific name I propose to retain for this form, as it is older than 

 either P. subawitus or P. pectiniformis of Lamarck. Martens 

 quotes it from Mergui. 



The external colouring of these two species is very similar, but 

 there is a feature within the valves which, in addition to the broader 

 sulci, seems to indicate that the species are distinct. I refer to the 

 colouring of the margin of the hinge-plate below the teeth. This 

 is almost invariably of a rich brown or reddish-brown colour. On 

 the other hand, in P. amboinensis, the species with broad ribs and 

 narrow sulci, this part apparently is never entirely coloured, but 

 occasionally a small brown mark is observable at one or both sides. 



In the series of specimens in the British Museum, the differences 

 are quite noticeable and the two forms are readily separable. 



256. LiMOPSis roRSKALii, A. Adams. 



Hab. Japan. 



The single valve described by Adams is small in comparison with 

 some of the specimens obtained at Aden by Major Yerbury. The 

 largest is 25 millim. long, 25^ from the umbones to the ventral 

 margin, and 13^ through the valves. The epidermis which remains 

 towards the outer margin is closely pilose and yellowish. The 

 interior of the dead valve from Japan was described as pale red ; 

 in the Aden specimens it is rich brown, paler or even whitish at the 

 circumference, and in the middle of the valves the rich brown colour 

 is more or less clouded with a thin whitish callus, which, however, 

 does not cover the muscular scars or the pallial line. Hinge-teeth 

 about 28 in number. 



257. Pinna bicolor, Chemnitz. 



Hab. Red Sea (C^emmYs:); Malacca (fieeve) ; M.^r^wi {Martens). 



Two valves from Aden exhibit the coloration described by Chem- 

 nitz ; one specimen agrees with Reeve's figure (Conch. Icon. f. 17), 

 and another example is almost entirely of a uniform whity-brown 

 colour, with the elevated ridges towards the apex obscurely tinted 

 olive-brown. The elevated scales upon the feeble ridges are few 

 and far apart. 



258. Pinna serra. Reeve. 

 Hab. Queensland. 



259. Pinna rigida, Dillwyn 1 

 Hab. West Indies. One valve only. 



260. Malleus albus, Lamarck. 

 Hab. Philippine Islands. 



