CLASSIFICATION OF PALEOZOIC INSECTS. 329 



Length of fragment of wing 25 mm., probable complete length 28 mm., breadth 7.75 mm. 

 Carboniferous beds of Mazon Creek, 111. (Mr. L. M. Umbach). 



The specimen figured on pi. 30, fig. 7, also belongs to this family, but too little of the 

 neuration is preserved to enable one to speak with any confidence of its exact position. 

 It would seem probable that it should fall here. The insect is exposed on a side view and 

 the wings overlap so as to confuse the neuration at the costal border, but the mediastinal 

 and scapular veins are plainly simple and the former ends on the costa and has few or no 

 branches. The body was elongated and the wings probably about 35 mm. long. It 

 comes from Mazon Creek, Illinois, and bears the number 2018 in the collection of Mr. R. D. 

 Lacoe. 



Genentomum ( yi'vos, 4'vtoh.ov ) S cn - nov - 



The wings in this group are large and elongated with coarse neuration and abundant, 

 somewhat feeble cross veins. The front is more ovate than the hind wing, the costal 

 margin being more arched, the tip apparently more pointed and the anal area more 

 excised. The mediastinal vein is long, at least two-thirds the length of the wing, and 

 sends abundant though not crowded branches to the costal margin. The scapular vein lies 

 very close to it and emits no branches until beyond it, when it sends off a few more oblique 

 ones and itself extends to the tip. The externomedian vein is separated by an unusual 

 interval from the scapular and emits several stout forked branches, which cover the apical 

 and the extreme outer part of the inferior border. The internomedian vein is forked once 

 or twice only in the front wing, the branches appearing similar to those of the preceding 

 vein ; while in the hind wing it bears many shorter and much more oblique inferior 

 branches. 



G-enentomum validum, sp. nov. PI. 30, figs. 2. :5. 



The only parts preserved in the single specimen known are the greater portions of two 

 wings, a front and a hind wing, widely separated from each other but in the same nodule. 

 In the front wing the greater part of the costal margin, including all of the mediastinal vein 

 and its branches, is destroyed, unless as is probable the first vein shown is the extremity 

 of this vein ; in the hind wing the branches of this vein are oblique, increasingly longi- 

 tudinal away from the base, and often forked and sinuous. In the front wing the exter- 

 nomedian vein is separated from the scapular by a space about equal to the interspaces 

 between its branches before they fork, and is connected with it by distant transverse cross 

 veins, breaking the interspace up into subquadrate cells; in the hind wing, the course of 

 the vein is not so straight, it is rather more widely separated from the scapular vein and, 

 besides the transverse veins, the interspace is traversed by a supplementary, longitudinal, 

 binding vein in the middle of the wing nearly a fourth the length of the latter; the 

 branches of the externomedian vein are more frequently and extensively forked in the 

 front than in the hind wing but do not differ much. The internomedian vein is soon 

 forked in the front wings and both branches ai>;ain dichotomize to a considerable extent, 

 while in the hind wing half a dozen simple arcuate branches, their concavities toward 



