786 MESSRS. MELVILL AND STANDEN ON [Nov. 13, 



Persian-Gulf region, we would say, as regards the Pelecypoda, that 

 the most distinctive and widely-spread family appears to be the 

 Tellinacea, between 40 and 50 species of the typical genus Tellina 

 lieing present, several endemic and hitherto unknown, others of 

 wide range. Veneracea are likewise plentiful, some, e. g. Tivela 

 ponderosa Koch, and Ocdlista multiradiata Sowb., being among the 

 finest of their race. The only Solenomya is peculiar, being also an 

 inhabitant of Patagonia. The members of the Arcacea ai'e freely 

 distributed, amongst them being two fine endemic Fectuncidi, 

 P. mashatensis Melv. and heroicus M. t St., this last now described 

 in this paper. In Nuculida?, Yoldia and Leda can boast of several 

 most interesting species, Ni(,cula being also jjresent, but not to so 

 prominent a degree. In Mytilacea, several Modiolce, Crenellce, 

 &c. occur, mostly of small size, but in some variety and refinement 

 of form. 



In Aviculidfe a few striking species occur, the most notable, of 

 course, being the local varieties of the Pearl -Oyster, an important 

 fishery of which exists in the Persian Gulf. Among the true 

 Oj^sters (Ost?-ea), some large and important forms are found, e. g., 

 0. ciicidlata Born, and iridescens Gray, the latter attaining a large 

 size. But to 0. toionsendi Melv., an endemic species discovered 

 about ten years ago by Mr. Townsend, adhering to the telegraph- 

 cable in the Gulf, must be given the palm, it being one of 

 the few Ostrece exhibiting real beauty both in sculpture, form, and 

 delicacy of coloration. Pecten toionsendi Sowb., a noble species, 

 Vola dorothece Melv., and a few deep-sea Aonussia must not be 

 passed without notice. Spondylus exilis Sowb. and S. gloriandus 

 M. & St. are likewise two conspicuous endemic sj^ecies, the former 

 to some extent allied to the Mediterranean ,S. gcedaropus L,, 

 though quite distinct. Indeed, close afiinities with South- 

 Eui'opean forms ai'e the characteristics of many species in this 

 fauna, seeming to point in frequent instances to a common 

 archaic ancestry. In the Lucinidas, Loripes victorialis Melv., a 

 most delicate milky-white transparent species, with close con- 

 centric lamelipe, is endemic ; and the same may be said of the 

 somewhat similarly ornamented Mactrinida tryphera* Melv,, from 

 the Persian Gulf. 



The Cardiacea a,re many in numbers, but few of conspicuous 

 size, Cardium fornicatmn Sowb. being perhaps the most inter- 

 esting; while the smaller C. centura-liratimn Melv., described below, 

 is a particularly delicately-sculptured abyssal shell. Among 

 the Myacea, Gari {Psamviobia) exhibits 13 or 14 species, some 

 endemic, all being varied in both sculpture and coloration. Some 

 large Pholadacea occur: Pholas hakeri Desh. (named after 

 the late Major Baker, the first recorder of Mollusca from 

 Karachi, in 1850), has a wide range over the northern shores, 

 and Ph. orientaUs Gm. occurs with valves sometimes 8 inches 

 in length. In the Anatinacea are one or two Anatince, four 



* Since this paper was written, this JIactriniila has been dredged by the 

 'Investigator' in deep waters south of the Gulf, thus extending its area of dis- 

 tribution. 



