ORDER ANOPLURA, OR SIPHUNCULATA 



213 



The thorax is wider than the head, but rather narrower 

 than the abdomen, the 3 component segments are not always 

 easy to distinguish. There are no traces of wings. The legs 

 are generally stout and coarse ; the tarsus consists either of 

 a single segment or of 2 indistinctly separated segments, and 

 ends in a remarkable stout hook-like claw, which bites against 

 a sort of " thumb " at the opposite angle of the tibia. In the 

 legs of a louse of the elephant, however, the legs are long and 

 slender, and the tarsus ends in two claws of unequal size. 



The number of abdominal segments ranges from 6 to 9 ; 

 in the female (Fig. 94) the last segment is bilobed ; but in 

 the male (Fig. 95) the abdomen ends bluntly, and the heavy 



Fig. 94. — Pediculus capitis, female. 



Fig. 95.-7^. capitis, male. 



spike-like penis projects beyond its tip. The spiracles are 

 very prominent towards the sides of the segments. 



The eggs, which are large and are known as " nits," are 

 stuck to the hairs of the host (or it may be to the clothing 

 in the case of man). The new-hatched young resemble the 

 parent in everything but size. 



Leeuwenhoek in the seventeenth century made some 

 interesting observations on the breeding of the human body- 

 louse {Pediculus vestimenti, Leach). He put two females 

 in his stocking, which was tied so as to prevent their escape. 

 Six days afterwards he found one of the insects with 50 

 eggs alongside, and another batch of 40 eggs probably 

 laid by the other insect, which had escaped. On killing the 

 insect that remained he found 50 more eggs in its body. 

 He left the eggs in his stocking for another ten days, when 

 he found 25 young lice, and then he abandoned his 

 observations in disgust. 



