40 Mr. C. J. Gahan on new Longicorn 



in which selection has been by far the more potent factor, so 

 much so that the intermediate grades between the two forms 

 have been so far eliminated as to be on the verge of 

 extinction. 



Salisbury, Mashonaland, 



May 1898. 



Postscript. — I have previously (Proc. Zool. Soc. 1897, p. 6) 

 suggested that the application of a distinctive scientific name 

 to each seasonal form of a dimorphic species is hardly more 

 reasonable than in the case of sexual forms, and that the 

 difficulty might be met by the general adoption of a set of 

 signs, similar to those used for the sexes, to represent the 

 extreme and intermediate stages. As 1 am not aware that 

 any such signs have yet been proposed, I make bold to 

 suggest the following, which I have found very useful in my 

 own notes : — 



Wet-season or summer <$ = 



Dry-season or winter <$ = Qj 



Intermediate S = & 



and similarly for the ? . Should it be desired to mention 

 only the form without reference to sex the circle and internal 

 sign alone might be used, e.g. dry-season form =©. The 

 system doubtless has its drawbacks, but these, I venture to 

 think, would be outbalanced by the advantage gained in pre- 

 venting the continual repetition of such cumbersome phrases 

 as wet-season form and summer form, neither of which cover 

 the facts of the case, and further in checking the undue 

 multiplication of varietal names. 



VII. — Descriptions of new Longicorn Cohojrtera from East 

 Africa. By C. J. GAHAN, M.A., of the British Museum 

 (Natural History). 



The new species of Longicorn beetles described in the 

 following paper are, with a few exceptions, from the collec- 

 tions made by Dr. J . W. Gregory during his expedition to 

 Mount Kenya and by Mr. C. S. Betton in the tract of country 

 traversed by the railway running inland from Mombasa. 



Xysirocera Ansorgei, sp. n. 



Capite, prothorace et corpore inferiore brunneo-testaceis ; elytris 

 osseis, fusco punctatis et maculatis; pedibus brunueo-testaceia 



