166 TERTIARY INSECTS OF NORTH AMERICA. 



render it more than probable that no Chrysopidse are yet known from the 

 European Tertiaries. It is therefore all the more interesting that we find 

 at Florissant four species of this group referable to two genera hitherto un- 

 known. (October, 1883.) 



The genera may be separated by the following table : 



Table of the genera of Chryaopid<v. 



Upper cubital vein of frout wing direct, bordered by comparatively iinit'orm cells 1. Palceochryaa. 



Upper cubital veiu of frout wing doubly bent in the middle, bordered by very unequal cells. 



* 2. Ti-ibochrysa. 



1. PAL^EOCHRYSA gen. nov. (TraAcac?, zpvo6?). 



The only materials for establishing this geuus are the wings, the 

 structure of which does not accord with any known living or extinct type. 

 The shape of the wings is much as in Chrysopa, and they are apically 

 rounded ; the costal area of the front wings, narrow at b«se, rapidly ex- 

 pands and then diminishes, being broadest within the basal fourth of the 

 wing. By the apical union of the costal and subcostal veins the area 

 terminates some distance before the apex of the wings, as in Ilypochrysa. 

 The cubital area is unusually broad, the anterior cubital vein running 

 through the very middle of the wing, and the posterior cubital rather nearer 

 the margin than to the anterior cubital, both continuing to the apex of the 

 wing ; in consequence of this and of the presence of only a single sector of 

 the radius there are no transverse series of gi-adate veinlets whatever, but 

 the secondary sectors are to be looked on as cross-veinlets uniting the prin- 

 cipal longitudinal veins ; one of the basal cubital cellules of the anterior 

 wings is divided nearly equally, as in Nothochrysa. 



It is difficult, perhaps, to say to which one of the modern genera it is 

 most nearly allied, but it appears to resemble Hjpochrysa as closely as any, 

 though it agrees much more with the fossil genus Tribochrvsa described 

 beyond, where the distinctions between the two are pointed out. 



Pal.eochrysa steicta. 



PI. 14, Figs. 13, 14. 



Little besides the wings can be made out in the single specimen with 

 its counterpart which represents this species. The front wings are a little 

 more than two and a half times longer than broad ; the costal margin, ex- 

 panded a little near the base, is beyond that straight until it slopes down- 



