189 



On the Pulex Irritans ; or Bed Flea, 



By W. H. Furlonge. 



{Read 2±th February, 1871.) 



The single family of the Pulicidse, to which the common or bed 

 flea belongs, is, I believe, generally classed with the Aptera, or 

 Aphaniptera, though it is, by some naturalists, referred to the order of 

 the Diptera. It is composed of very numerous species, which are found 

 upon a vast number of animals, on which they are parasitic. Many 

 of these species present peculiarities of form and structure of great 

 interest, and are found to vary in the most remarkable manner with 

 the species of the animal they infest. The field of observation yet 

 to be explored, with reference to the Pulicida3,'is a very extensive 

 one, and although the present paper relates entirely to the one 

 species, I may just remark, as illustrative of the interest of the 

 subject, and the varieties of structure found in the different 

 species, that certain fleas, — notably those of the mole, mouse and 

 bat, — are either entirely destitute of eyes, or possess them only in 

 the most rudimentary form, — the antennae, on the other hand, as if 

 in compensation, — being very largely developed; — that the fleas 

 found upon many kinds of birds are furnished with plumose an- 

 tennas of great beauty, which in many cases are carried erect ; — 

 and that the position, numbers, and form, of the spinous processes 

 and hairs of the fleas of different animals, present such well-marked 

 and constant variations, that, in many cases, it is quite possible to 

 identify, with, absolute certainty, the species of the animals upon 

 which they have been found. With these general remarks upon 

 the family of the Pulicidae, I now turn to the special species which 

 forms the subject of the present paper. 



The general form and outline of the bed flea, or Pulex irritans, is 

 remarkably symmetrical, and even graceful. Although encased in 

 a suit of mail of the most complete description, such is the won- 

 derful adaptability of the parts composing it, that the most active 



Journ. Q. M. C. No. 15. o 



