the material in my own hands, it would of course be useless and out of 

 place to attempt to designate such portions, since originality can not be 

 claimed for any such work, though the author may riglitly be held re- 

 sponsible for presenting the matter as a vvhole. 



The arrangement given is in descending order, but it will be im- 

 [)Ossible to follow this in the order of giving the generic syno[)ses. 



Including the iMallophaga and the Thysanofttcra {Physapoda of 

 Packard) we have no comprehensive definition of th^ group. Excluding 

 the>e, we miy say the Huniptera include those insects prc)vide(.l 

 with a rostrum or beak formed from the labium and enclosing four ex- 

 tensile setae which form a sucking tube, aUjng with wings usually four in 

 number which are either all m imI)ranous, or the fore ones partially or 

 entirely coriaceous. (In CoccHce. there are two in the males only, and in 

 s )me other groups they are absent or ruilimentary in one or both sexes.) 



This group which we may call HeniipUra gtimiiu is clearly divieled 

 by the position of the head and the structure of the wings into two sub- 

 t)rders, the Hdleropkra and Homoptera. 



A third sub-order, Parasila, includes the suctorial lice infesting 

 mammals, these apparently having about equal affinities for the two other 

 sub-orders, but combining with neither in being wingless and the beak 

 not jointed. 



The other groups are at present most conveniently grouped here, 

 and may be ranked also as sub-orders though structurally there can be 

 little question that they must bear a more distinct relation to the Hemlp- 

 lera proper. 



The Thvsanoptera (or Phvsapodix) are minute insects usually less 

 than 2 millimeters in length; with four very narrow delicately fringed 

 wings which lie flat on the back, with free palpigerous mouth parts, anl 

 tarsi without claws; the terminal joint being vesicular. 



The MaUophaga are wingless parasitic insects living on birds or 

 mammals, with free biting mouth parts, antenniie of three to five joints 

 and presenting some resemblance to the wingless Psocidit, and by 

 some authors grouped with the Pseudo-Neuroptera. 



It is intended to include in these synopses only the North American 

 genera, and the tables must not be considered as applicable in a larger 

 range. The characters also, here mentioned are those of most import- 

 ance as related to the groups to be here included. 



Perhaps in no other order of insects is there such diversity of modi 

 fication in the several structural elements, and this diversity is accom- 

 panied with extreme lack of constancy, so that the clear definition of 

 groups is rendered difficult. 



