on the Structure of the Mouth in Pediculus. 227 
real mandibles transformed) are protruded; these are, towards their 
points, united by a membrane so as to form a closed tube, from 
The larger figure represents 
the parts of the mouth, in a 
large specimen of Pediculus vesti- 
menti, entirely protruding, and 
seen from above, magnified 160 
times: a a, the summit of the 
head, with four bristles on each 
side; 5 6, the chitinous band, and 
ce the hind part of the lower lip— 
such as they appear through the 
skin by strong transmitted light ; 
dd, the foremost protruding part 
of the lower lip (the haustellum); 
ee, the hooks turned outwards ; 
f; the imner tube of suction, 
slightly bent and twisted ; the two 
pairs of jaws are perceived on 
the outside as thin lines; a few 
blood-globules are seen in the in- 
terior of the tube. 
The smaller figure is a repeti- 
tion of Erichson and Simon’s 
figure of the organs of the mouth 
in P. capitis: a, the haustellum ; 
b, the mandibles; c,the palpi. (‘Die 
Hautkrankheiten,’ tab. 7. fig. 4.) 
which, again, is exserted* the second pair of setze or maxillee, which 
* It will scarcely be possible to ascertain the details of the protruding 
mechanism by examination of the human species alone, as the parts are 
too small in these species. I had therefore wished to compare living spe- 
cimens of the larger species inhabiting our domestic animals, particularly 
the horse and the pig; but I have been unable to obtain any at present. 
Very likely the mechanism may prove rather complicated. Without in- 
tending a close comparison, I shall here only, as an instance, advert to the 
exceedingly remarkable mechanism discovered by Lyonnet in Melophagus 
ovinus. (See his posthumous papers in the ‘Mémoires du Mus. d’ Hist. 
Nat.’ tome xvii. p. 233, pl. 9.) 
15* 
