27 



APTERA. 



Insects of this order are without wings, and the name is derived 

 from two Greek words, a, privative, and TTTephv, wing, indicating the 

 negative character which constitutes this order.* It consists of Fleas 

 and Lice. The Flea (Fukx), of which De Geer formed a separate 

 group, and called Suctoria, includes several species. 



The common flea {Pulex irrifans, 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 

 between one's nails. 



Its head, small in proportion to the body. Fig. 17. 



is compressed, and carries two small antennse, ^^^^ {Puiex trntans). 

 of cyHndrical 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 under- 

 neath two long sharp lancets, with cutting and saw-like edges. It is 

 with this instrument that the flea pierces the skin, irritates it, and 

 causes the blood on which it lives to flow. 



This bite, as every one knows, is easily recognised by the presence 

 of small darkish red spots, surrounded by a circle of a paler colour. 



* It is probable that one day the order Aptera will be superseded.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 Blainville, 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 " Traite de Zoologie Medicale " of these two last authors. 



