374 Mr. C. J. Gahan on the Prionidous 



Type in tlie collection of the Zoological Museum of the 

 Imperial Academy of Sciences at St. Petersburg. 



This species is evidently aquatic, like Crossojjus fodiens, 

 the fringes of the manus and pes being even better developed 

 than in that species ; but in all generic characters it agrees 

 with those of the genus Sorex. While agreeing with Sorex 

 pahish'is from tlie adjoining continent of America in external 

 characters, it differs from it in the proportions of its teeth, 

 resembling in tliis respect the section of which 8. vulgaris is 

 typical, while S. palustris agrees with those represented by 

 S. vacjrans. No better proof could be afforded of the useless- 

 ness of retaining Neosorex as a distinct genus for the Ameri- 

 can species characterized by the possession of swimming- 

 fringes in the digits, while the tail is simple, as in Sorex. 

 These species are in fact aquatic forms of the genus Sorex. 



LIII. — Note on the Variation of the Mandibles in the Males 

 and Descriptions of the Females of the Prionidous Genera 

 Priotyrannus and Cacosceles. By C. J. Gahan, M.A., 

 Assistant, Zoological Department, British Museum. 



The variation in the form of the mandibles within the same 

 species of certain genera of Prionidie has doubtless been 

 known to many entomologists who have studied the family, 

 though no special attention seems to have been called to it. 

 The variation itself is probably of greater degree than has 

 been hitherto suspected. Lacordaire, at least, in his treat- 

 ment of the Prionidffi, does not give evidence of his knowledge 

 of any great variation. 



The subject has lately been brought under ray notice while 

 working out the Longicornia of a collection made by G. F. 

 Hampson, Esq., in the Nilghiri Hills, South India. 



One species was represented by four specimens, three of 

 which have mandibles so different in form from the fourth, and 

 in other respects are in such complete agreement with it, that 

 I was at first led to believe that I had to deal with the two 

 sexes. But all four proving to be males, it then seemed to 

 be a case of variation in the mandibles parallel to that which 

 occurs in many genera of LucanidfE ( Odotitolahis, for example). 

 The species was referable to the Prionus mordax of White, 

 on which Thomson has founded his genus Priotyrannus. The 

 single specimen with incompletely developed mandibles agrees 

 with the male type from which White described the species. 



