251 



OBSEEVATIONS ON THE GENUS CLEA, WITH THE DESCRIPTION 

 OF A NEW SPECIES. 



By Edgak a. Smith, F.Z.S., etc. 



Read February ith, 1895. 



This genus was originally described by Mr. A. Adams in the Proc. 

 Zool. Soc. for 1855, p. 119. As he had neither the animal, nor the 

 operculum, he was unable to suggest its true systematic position ; 

 but he shrewdly remarked its resemblance to " a fluviatile Buccinum.'''' 

 In conjunction with his brother, he subsequently ' referred it to the 

 subfamily Melanopsinae. 



Dr. Brot,- however, has since shown, by an examination of the 

 radula, that this mollusc clearly belongs to the Rhachiglossa and is 

 closely allied to the Buccinidfe ; indeed, conchologically and with 

 regard to the operculum, it is scarcely separable from Cominella? 



The British Museum has recently been presented, by Mr. H. Fulton, 

 with two specimens of a shell from the Island of Balabac, which 

 M. Crosse in 1886 descril)cd under the name of Quadrasia Hidalgoi. 

 Like Clea, it is an inhabitant of fresh water. He considered it a form 

 of Planaxidae, and made no reference whatever to the genus Clea. 

 This evidently must have been an oversight, for the two forms are 

 undoubtedly congeneric, indeed very closely related specifically. Tliey 

 correspond so closely in general form, in their periostracum, their 

 apertures, and opercula, that I have not the slightest hesitation in 

 placing them in one and the same genus. 



The known species of Clea are — 



1. Clea nigricans, A. Adams. 

 Clea nigricans^ A. Adams. — Proc. Zool. Soc. 1855, p. 119; H. and 

 A. Ad., Gen. Moll., pi. cxxxvii, fig. 8; Brot, Journ. de 

 Conch. 1876, p. 350, pi. xii, figs. 2, la (operculum), fig. 4 

 (radula) ; Kobelt, Illust. Conchylienbuch, pi. xlvi, fig. 33. 

 Melania nigricans^ Reeve. — Conch. Icon., figs. 231^-5. 

 JHemisinus nigricans, Reeve, op. cit. figs. 2ba-d. Length (3 volutions) 

 28, diam. 16 mm. 



Hab — " The River in Sarawak Borneo" (A. Adams); " I. de Rio" 

 and Sadon, Sarawak (Issel). 



Var maxima. — Brot, op. cit. 1881, p. 159, pi. vi, fig. 4; Bock, 

 Proc. Zool. Soc. 1881, p. 635. Larger than type, of a uniform brown 

 colour, and covered with distinct, but superficial striae parallel with 



1 Gen. Eecent Moll., vol. ii, p. 623. 



2 JoTirn. de Conch. 1876, pp. 348 351. 



3 Cooke (Cambridf^e Nat. Hist., iii, p. 16) has suggested, since this was written, 

 the probable derivation of Clea from Cominella. 



