412 Mr. S. H. Scudder on new Genera 



distance from, and nearly parallel to, the costal border, in the 

 outer half constantly but gradually approaching it, emitting 

 numerous oblique, generally simple branches ; the vein ter- 

 minates in the middle of the outer half of the wing, and shows 

 no such peculiarities at its tip as characterize 0. reticulata of 

 Europe. The scapular vein is also not so peculiar as there ; 

 it runs in near proximity and parallel to the mediastinal 

 vein, but there is the same slight bend in its course at the 

 base of the principal branch ; the mass of the branches, 

 which are fewer than in 0. reticulata, do not arise as there 

 from a vein emitted abruptly from near the base of the second 

 branch, to which they are inferior, but from the principal 

 branch itself, to which they are superior. The interno- 

 median vein terminates at about the end of the middle third 

 of the wing, and has only a few branches. The externo- 

 median branches all terminate on the inner margin. The 

 length of the wing is 19 millim., its breadth 7 millim. 



Carboniferous beds of Mazon Creek, Illinois (R. D. Lacoe, 

 No. 2039). 



Petrablattina wqua, nov. sp. 



Mediastinal vein terminating scarcely beyond the middle of 

 the costal margin, with numerous, closely crowded, simple 

 branches ; scapular vein terminating above the tip of the 

 wing, and beyond the basal curve nearly straight, with four 

 or five singly forking branches ; branches of externo-meclian 

 vein straight, superior, mostly simple, parallel to the main 

 scapular vein ; the interno-median area extending to some 

 distance beyond the middle of the wing. It is a tolerably 

 large species, the wing measuring 24 millim. in length and 

 10 millim. in breadth. 



Triassic beds near.Fairplay, Colorado. 



Petrablattina Meieri } nov. sp. 



Mediastinal vein terminating a long way beyond the middle 

 of the costal border, with comparatively distant, usually 

 simple branches. Scapular vein terminating just below the 

 tip of the wing and beyond the basal curve, gently arcuate 

 throughout, with branches similar to those of P. eequa, but 

 occupying a larger area. In consequence the externo-median 

 area is of less importance than in P. cegua, and it has but 

 few branches, which appear to be generally simple and 

 slightly declivent, though superior. Unfortunately this por- 

 tion of the wing in the single specimen known is very obscure. 

 The interno-median vein is not preserved in its outer portion, 



