30 AN ACCOUNT OF BRITISH FLIES. 
liquor potass@, then washed and soaked again in ¢urpentine and oil 
of cloves. 
Length of P. zrritans, about 1 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 /arve are pearly white and very active ; several hairs on each 
segment ; head slightly chitinous and brown ; two short, one-jointed 
antennze. The last segment armed by two recurved brownish spines. 
They may be found in the dust, etc., in the crevices of boards. 
The pup are enclosed in a silken cocoon and are also found in 
dust. 
The larve 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,” Aptéres,* 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, Dugts (=P. serraticeps, Gerv.). 
The “ Hundefloh” of the Germans. Resembles P. zrritans, but 
is smaller (4 lin.) and paler in colour. Coxe bristly ; femora devoid 
of bristles and hair. Tibiz thick. The legs generally shorter than 
in zrritans. 
The fifth and second tarsi the longest in the two front legs; the 
first and fifth, in the hind leg, as in ivritans. The ji/th 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, secdnd joint from 
base the largest. Mentum small. There is a comb-like fringe on 
* Vol. iii., p. 366, note. 
