ORDER PLA /)/'/ /.•/.'. I. 





meso- and metanotura are remarkable on account <>f the 

 imperfectly Eormed scuta and scutella, the latter being in- 

 definite in outline, though large. The cl 

 Bterna) are large and broad; and there are often elev< 

 ments in the abdomen. The order re< name from 



thr fact that the wings are usually laid flat upon the back 

 v hen the insect is at rest. 



The bird-lice (Mallophaga), though usually associated 

 with the true lice (which are wingless parasitic Eemiptera), 

 in reality seem to be degraded, wingless Platyptera, and in 



Flo. 49.— Teen* i, white mu. o.larva; b. winged n irorker; d, 



Bold Female; /, nymph or pu 



the shape of the body and mouth-parts arc more nearly 

 allied to the family PsocUIcb, which iucludcs the death- 

 tick, than any other group of insects; h< 

 these parasites as Forming a sub-order of the oup. 



All the insects of this order have some remar iliar- 



ities. The stone-flies or Perlid», which as la re in the 



water and Wreathe by external tufts of gil - - on the 



under side of the thorax, in some cast -. is in tl 

 Pteronarcys, retain them in the winged state. 



