110 Proceedings of the Biological Society of Washington. 



ment for basing them on the oldest genera, but on the contrary 

 strengthens it since it is clearly evident that this principle itself 

 guided the founders of most family names. When selection of 

 the oldest family name is made the exact form of the name is 

 ignored, and there may be chosen as a base a name quite unlike 

 our modern standardized family names. This being true and 

 the effort being merely to find the earliest group name, why not 

 select as root name the name which has genuine priority, namely 

 that of the earliest genus especially since in many cases this has 

 about the same scope as what we now regard as families. This 

 name embodies the first effort at classification in the group 

 concerned and formation of the family name from it is fitting 

 recognition of pioneer work. 



Hence I prefer for the group of leaf-hoppers here considered 

 the name Eupterygidae, based upon the oldest genus, Eupteryx, 

 and I put it in family form, because I believe the group can logi- 

 cally be treated only as a family. In keys to leaf-hoppers this 

 group is contrasted to all others by the veins of the tegmen 

 running without branching or juncture of any kind (except 

 theoretical or rarely actual juncture at base) , to the apical cross 

 veins, there being therefore no anteapical cells. This is a clear 

 cut and important character separating the Eupterygidae from 

 all other leaf -hoppers. Moreover it is one scarcely subject to 

 intergradation . It is supported by another peculiarity in vena- 

 tion which distinguishes this group from all Homoptera 

 Auchenorhynchi, namely the possession of only one vein on 

 disc of clavus, the first anal practically coinciding with claval 

 suture and the third anal with claval margin . Ocelli are seldom 

 conspicuous, sometimes lacking. 



A feature of less importance, but one which has not received 

 attention from writers on Eupterygidae is the general occurrence 

 in some genera of costal plaques. These are encrustations of a 

 substance, between pruinosity and wax in consistency, on defi- 

 nite elliptical areas at about the middle of each costa. They 

 suggest the much heavier and more conspicuous plaques observed 

 on many specimens of Oncometopia. The areas on which these 

 plaques occur in Eupterygidae are regarded as definite, because 

 of repeated observations of their location, because they may be 

 recognized when the encrustation is lacking, and most important 

 of all because these areas are often distinctly colored. The 



