82 ANIMAL PAKASITES. 



Second Family Crab-Louse = PHTHIRITJS. 



Corporis regiones ad unam fere massam globulosam coalitce, 

 thorace vix distinguendo, brevi, lato ; abdomine lato et in marginum 

 utroque later e cum 8 segmentorum imcisionibus ; antennis longioribus; 

 pedibus incequalibus, anterioribus 2 sine talo et uncino in talum 

 mobili (pedes ambulatorii) , posterioribus 4 ut in pediculis, cum talo 

 et uncino in talum mobili (scansorial feet). 



1. The common Crab-Louse = Phthirius pubis. 



Synon. : Pediculus pubis, inguinalis ; Morpion. 



It has a fiddle-shaped head, with a prominent, rounded fore- 

 head and a broader proboscidal aperture than the common louse, 

 and a somewhat projecting vertex with waved (buchtig) sides in 

 the neighbourhood of the antennae ; a rather short, dilated, and 

 rounded occiput ; very small, somewhat prominent eyes, imme- 

 diately behind the filiform antennae, which are slightly hairy, fi\ 7 e- 

 jointed, and gradually diminish in size, with the fourth joint 

 rather smaller than the third and fifth ; with a very broad and 

 flat thorax, emarginate at the insertion of the head, with three 

 pairs of feet and a stigma between each of the first and second 

 pairs of feet ; and with a flat, cordate abdomen, amalgamated 

 with the thorax. If we go according to the stigmata, we find 

 first an apparently simple anterior segment which bears three 

 stigmata ; we must, therefore, certainly suppose that this segment 

 consists of three which have become fused together. It is 

 separated from the following segments by the lateral, verruciform 

 lobe, which diminishes in a conical form towards its free extremity, 

 where it is clothed with hair, and exhibits six bristles. This lobe > 

 which has some similarity with a rudimentary foot, is followed by 

 three similar ones, each of which bears a stigma and which 

 becomes longer posteriorly. The second stump bears six bristles 

 at its free extremity, the third six to eight, and the fourth 

 always eight to ten. This last lobe is followed by the terminal 

 segment, which is notched in the female in the same way as in 

 the common louse. It bears five larger bristles on the hind- 

 most free apices, and also towards the median line a pair of 

 very short stumps, and also on the dorsal surface six longer 

 bristles. Here are placed the vagina and the anus. In the male 

 the hinder part is rounded. On her ventral surface the female 



