APTERA. 
Insects of this order are without wings, and the name is 
derived from two Greek words, «, privative, and mrepov, wing, 
indicating the negative character which constitutes this order.* 
It consists of Fleas and Lice. The Flea (Pulex), of which 
De Geer formed a separate group, and called Swuctoria, includes 
several species. 
The Common Flea (Pulex irritans, Fig. 17) has a body of oval 
form, somewhat flattened, covered with a 
rather hard horny skin of a brilliant chestnut 
brown colour. It is the breaking of this hard 
skin which produces the little crack which 
is heard when, after a successful hunt, one has 
the happiness to crush one of these parasites Fig. 17.—Flea (Pules 
between one’s nails. re): 
Its head, small in proportion to the body, is compressed, and 
carries two small antennz, of cylindrical form, composed of 
four joints, which the animal shakes continually when in motion, 
but which it lowers and rests in front of its head when in a 
state of repose. The eyes are simple, large, and round. The 
beak is composed of an exterior jointed sheath, having inside 
it a tube, and carrying underneath two long sharp lancets, with 
cutting and saw-like edges. It is with this instrument that the 

* It is probable that one day the order Aptera will be superseded. The 
absence of wings is not really a character of great value. De Blainyille, Mollard, 
Pouchet, Van Beneden, and Gervais, have made several attempts in that direction. 
The fleas have been placed among the Diptera, and the lice among Hemiptera in 
the “‘ Traité de Zoologie Médicale”’ of these two last authors. 
