30 AN ACCOUNT OF BRITISH FLIES. 



liquor poiasscc, then washed and soaked again in turpentine and oil 

 of cloves. 



Length of P. irritaiis, about i lin. This is one of the commonest 

 fleas, and is parasitic on the human race, especially in Europe, 

 where it extends from the Arctic regions to the warmest parts of 

 the Continent. 



The larvtt are pearly white and very active ; several hairs on each 

 segment; head slightly chitinous and brown; two short, one-jointed 

 antennae. The last segment armed by two recurved brownish spines. 

 They may be found in the dust, etc., in the crevices of boards. 



The pupje are enclosed in a silken cocoon and are also found in 

 dust. 



The larv?e may also inhabit the human subject, and are said to 

 feed upon the scurf of the hair. 



Innumerable accounts of the Herculean strength of the common 

 flea have been written by English, French, and German authors, so 

 it is unnecessary to add more to this subject here. Perhaps the 

 account given by Walckenaer, in his " Histoire Naturelle des In- 

 sectes," Apteres,''' where he describes the military exercises gone 

 through by thirty fleas, is one of the best. The enormous strength 

 and power of leaping displayed by these somewhat obnoxious insects 

 can be comprehended when we consider that if a lion had the same 

 proportion of strength to the size of its body it could leap two-thirds 

 of a mile ! 



Pulex canis, Duges { = F. serraticeps, Gerv.). 



The " Hundefloh " of the Germans. Resembles P. irritans, but 

 is smaller (4 lin.) and paler in colour. Coxs bristly ; femora devoid 

 of bristles and hair. Tibise thick. The legs generally shorter than 

 in irritans. 



The fifth and second tarsi the longest in the two front legs; the 

 first and fifth, in the hind leg, as in irritans. Theffth being the 

 longest in the front legs in this species ; not the second, as in the 

 common flea. 



The ungues are large and broad, dark in colour, and fringed with 

 black spines on both sides. Last tarsal joint armed with five spines 

 on the under surface. Head small, compressed, ciliated with bristles; 

 punctate behind. Eyes small and lateral. Mandibles long and 

 slender, transparent, central rib well marked. Tongue same length 

 as the mandibles. Maxillary palp, robust pilose, second joint from 

 base the largest. Mentum small. There is a comb-like fringe on 



* Vol. iii., p. 366, note. 



