168 



Note on some Peculiarities of a Flea. 



By E. T. Lewis, F.R.M.S. 



{Read June 2oih, 1880.) 



It will, no doubt, be remembered by those who were present at 

 the last meeting of the Club, that a remarkably large specimen of 

 Pulex — species undescribed — was then presented to the Cabinet, on 

 behalf of Mr. J. G. Tatem, of Reading, Thinking that perhaps a 

 drawing of it might be useful for future reference, as an aid to its 

 identification, I took home the slide for the purpose of making one. 

 The sketch — merely made with pen and ink — is, I fear, somewhat 

 rough, but it is, I believe, made accurately to scale under a lin. ob- 

 jective, by Dr. Beale's reflector, and is offered to the collection of the 

 Club for what it may he worth. 



Mr. Tatem mentioned, in the note which accompanied the slide, 

 that it was interesting as containing, within the body of the flea, four 

 specimens of Acarellus, which he had described and figured in the 

 M. M. J., for December, 1872. The careful attention, however, 

 which drawing demands, soon showed that the body of the insect 

 was tenanted by a much greater number of these minute creatures — 

 how many it is not quite easy to determine with accuracy — but the 

 mean of six separate counts under a lin. objective, gives the number 

 as 51, distributed throughout the abdomen. (Those situated in the 

 6th and 7th segments only, are lightly indicated in the sketch). 



My attention was, however, chiefly arrested by a pair of organs 

 or processes situated immediately above the Pygidium, not alto- 

 gether unlike Palpi, and the use or nature of which is by no means 

 clear. One of them is seen upon the upper surface, and the other 

 is by deeper focussing fairly well seen through the double thickness 

 of the flea's cuticle. A drawing of the Pygidium and its appen- 

 dages is annexed to that of the Flea, and will convey some idea of 

 these processes and their well-marked structure. 



On communicating the observation to Mr. Tatem, he replied as 



