KIIYNCOTA. 
27 
entirely in the water, but the majority are aerial. The 
Order is divided into three sub-orders, viz. :—the 
Anoplura , the Heteroptera , and the Homoptera. The 
Anoplura contain all those insects commonly known as 
lice, which are parasitic on man and other animals. 
The suctorial louse ( pediculus ), of which four species 
are parasitic on man, belong to this sub-order ; it also 
includes all the biting bird-lice, which by some writers 
have been made into a separate order under the name 
of Mallopkaga. But it is better to arrange the bird- 
lice, notwithstanding the 'difference of structure in the 
mouth, with the Anoplura. Nearly 500 different forms 
of these parasitic insects, formed on the plan of the 
common louse, have been described. Almost every bird 
has its parasite accompaniments, and several of the 
Mammalia have theirs. Some animals have only one 
species of parasite peculiar to itself, others have 
several species; on domestic cattle three species are 
found, on the horse two, on the ass three ; on the 
golden eagle four, on the white-tailed eagle no less than 
six species of parasitic louse occurs, and water birds are 
as subject to them as land birds. These biting-lice do 
not suck the blood like the common pediculus, but eat 
the delicate parts of the feathers or hair. The Anoplura 
undergo no metamorphosis; the eggs are hatched in a 
few days, and the young are soon capable of repro¬ 
duction, hence the enormously rapid increase where 
strict measures are not adopted for their extermination. 
I believe it was Leeuwenhoek who computed that in two 
months two female lice could produce ten thousand ! 
The Heteroptera include those insects of the Order 
Rhyncota, whose anterior wings are heterogeneous, i.e. y 
