— 22 — 



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 rightly be held re- 

 Sp »nsible for presenting the matter as a whole. 



The arrangement given is in descending order, hut it will he im- 

 possible to follow this in the order of giving the generic synopses. 



Including the Mallophaga and the Thysannptera {Physapoda of 

 Packard) we have no comprehensive definition ofth • group. Excluding 

 these, we may say the Hsmiptera include those insects provided 

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

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

 number which are either all membranous, or the fore ones partially or 

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

 some other groups they are absent or rudimentary in one or both sex< s.) 



This group which we may call Hemiplera genuina is clearly divided 

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

 orders, the Hderoptera and Homoptera. 



A third sub-order, Parasita, 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 the}- must bear a more distinct relation to the Hemip- 

 tera proper. 



The Thysa?ioptera (or Physapodd) 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, and 

 tarsi without claws; the terminal joint being vesicular. 



The Mallophaga are wingless parasitic insects living on birds or 

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

 and presenting some resemblance to the wingless Psocidae, 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 

 lication 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. 



