PARASITES. 229 



alive, and on placing it for observation on a smooth earthenware 

 saucer I noticed that it did not get on very well, but on presenting 

 it with a hair it immediately grasped it and appeared much more 

 at home. The claws of the female are similar, but more slenderly 

 formed and finer pointed. In the male body or clothes' louse the 

 claws are similar to those of the female head-louse, and in the 

 female more slender ; and in the crab-louse, in each sex, the 

 anterior legs appear to be more adapted for walking, but the 

 hmder four are exceedingly robust, and well adapted for grasping 

 and climbing. The mouth parts in each of these three varieties 

 appear to be very similar, and also in the genus H(zmatopinus^ 

 which infest some of the lower mammals. 



We now come to the Mallophaga — the biting, or bird lice. 



In these the metamorphosis is very slight. They creep about 

 near the surface of the skin, amongst the hairs and feathers, and 

 usually do not come to the surface, so that they are not readily 

 detected. Most of them live on birds and have generally two 

 claws to the feet, whilst those infesting mammals have mostly only 

 one. The mouth parts are on the under-side of the head. The 

 upper lip is frequently of a remarkable scraping form and the 

 mandibles toothed for cutting. Most of them have small forelegs, 

 usually drawn towards the mouth to manipulate the food, so that 

 sometimes the body looks as if it had only four legs. It should 

 be noted that these Mallophaga, though called bird-lice, are quite 

 distinct from the true lice, which, as I pointed out before, live by 

 suction, though they are often found with them, and it may be 

 added that, in a state of nature, it is believed they rarely cause 

 any annoyance to their hosts. 



1 must apologise if I have been too reiterative in my descrip- 

 tions, but my object has been to describe plainly the mouth parts 

 and the method of using them by the aforesaid parasites. 



The rapidity with which Plant Lice multiply is marvellous, and 

 perhaps not sufficiently recognised. According to the calculations 

 of one great scientist, five generations proceeding from one mother 

 produced 5,904,900,000 in a season, and as many as forty genera- 

 tions have been known to proceed from one mother. 



