CLASSIFICATION OF PALEOZOIC INSECTS. 341 



which it is evident that while the wing has much the general form and proportions of a 

 modern Pachytylus its neuration is altogether different. The mediastinal vein ends in the 

 margin a little beyond the middle of the wing. The strong and prominent gently arcuate 

 scapular terminates at the upper tip ; from it is thrown off before the middle of the basal 

 half of the wing a simple branch parallel to itself, which supports numerous, parallel, 

 oblique branches, the innermost of which strikes the middle of the outer half of the 

 lower border. The externomedian and internomedian ofhhoots, similar and parallel to 

 those of the scapular branch, are comparatively insignificant and divide about equally 

 between them the space between the scapular and anal veins which latter strikes the lower 

 margin below the origin of the first offshoot of the scapular branch. An additional proof 

 of its position here is the presence of a long longitudinal cross-vein uniting the base of 

 the main scapular branch with the externomedian branch, as in Brodia. 



m Pachytylopsis Persenairei. PI. 31, fig. 7. 



Pachytylopsis Persinairei DeBorre, Ami. Foe. Ent. Belg. xvm. 5-6. pi. 5, fig. 1 ; — 

 Giard, Bull. Sc. Hist. Litt. Nord, vn, 121-122. — Van Volxem, Comptes Rend. Soc. Ent. 

 Belg. (2) xxiv, 20-26. 



Carboniferous beds of Mons, Belgium. 



Lithentomum Scudder. 



This genus differs from all the others placed in this group in the presence of only a 

 single offshoot of the scapular branch; and although this point \< uncertain from the 

 imperfect nature of the single fragment, it seems improbable from what is preserved that 

 more can find a place. It agrees, however, in all other features with the family and 

 seems to find its place here. 



Lithentomum Harttii. 



Lithentomum Harttii Scudd., Dev. Ins. New Br., 22-24, pi. 1. fig. 3, where earlier refer- 

 ences are fully given ; — Hagen, Bull. Mus. Comp. Zool., vin, 278 ; Scudd., Earl. Winged 

 Ins. Amer., 4, pi. fig. 2-3. 



Devonian beds of St John, New Brunswick. 



Chrestotes Scudder. 



The termination of the mediastinal vein in the border and not in the scapular shows 

 that this insect cannot be referred to the Palaeopterina as formerly supposed by me. Its 

 place seems to be here in the neighborhood of Ilemeristia, though it differs widely from 

 that in the character of the scapular branch, and is peculiar for the deep impression of the 

 principal anal vein. 



Chrestotes lapidea. PL 31, fig. 2. 



Chrestotes lapidea Scudd., Geol. Surv. 111., in, 567, fig. 2. 



In the figure formerly given the engraver obscured the venation by numerous lines 

 parallel to the veins. The one now given is from a sketch taken by myself at that time. 

 Carboniferous beds of Mazon Cr.. Morris. Illinois. 



