130 AN IXTKODL'CTIOX TO IOLQGY. 



males at the Coccid.e present a remarkable exception in the nature 

 of their transformations, the metamorphosis being a complete one. 

 This order includes three well-marked groups; these are ranked 

 ib-orders. and are distinguished as follov. 



TABLE OF SUB-OKI>F.k> OI 1 1 KM JI'TERA. 



A. \Vi:^less Hemiptera, parasitic upon Man and other Mammals, with a fleshy 



unjointed rostrum.* 1. PAR A 



A.\. Hemiptera \vith or without win^s, but with a jointed rostrum. 



H. Wiii^s of the same thickness throughout, and usually sloping at the sides 

 of the body; rostrum arising from the hinder part of the lower side of 

 the head; head without neek. and so closely applied to the prot : 

 that the first pair of coxae articulate with the cheeks. 11. HOMOIM 

 BB. First pair of wings thickened at the base, and with thinner extremities, 

 which overlap on the back ; rostrum arising from the front part of the 

 head ; head (except in t'(-/s/i/- and Xntont'ctMu-) with a more or les 

 tinct neck, so that the cheeks and the first pair of coxae do not touch 

 each other. III. HETEROPI \ KA. 



Sub Order I. PARASITICA. 



The Parasltica includes certain parasites of Man and other Mam- 

 mals, commonly known as lice. All the species which have been 

 found in the United States belong to a single family, the l\*dicu- 

 lidic. \Ve will not, therefore, enter into a discussion of the charac- 

 ters of the sub-order, but pass directly to a study of this family. 



Family I. PEDICU Li I >.!:.+ 

 (Lice.) 



The lice are very small, \\ingless insects, which live on the skin of 

 Mammalia, and suck their blood. The mouth is furnished with a 

 fleshy, unjointed proboscis, which can be withdrawn into the head, 

 or extended to a considerable length. Within this proboscis are 

 two protrusiblc knife-like stylets; and at its base, when extended, 

 there is a wreath of re-curved hooks. These hooks serve to anchor 

 firmly the proboscis when inserted in the skin ot the infested ani- 

 mal. The ( two in number, small and simple. The antenna- 

 have tu nts. The leg's are joined to the outer margin of the 



* This is true of all forms that have IK-CM found in the t'niu-d States. Hut in the 

 genus /Wr< /<////.( the rostrum is three-jointed. Two species of this i^eiius are known; 



; one in the \V< the other in China, 



f J'tittiulns, a I 



