S. H. SCUDDER ON PALAEOZOIC COCKROACHES. 123 



regularly convex ; the inner margin is straight, excepting for the fulness of the anal area, 

 but a large fragment of the apex of the wing is wholly lost. The veins originate from a 

 little above the middle of the base, and have a gentle basal arcuation. The mediastinal 

 vein runs in close proximity and subparallel to the costal margin, constantly but very grad- 

 ually approaching it, emitting numerous oblique branches ; in the basal half of the area the 

 branches are forked half way to the margin, and between the forks are other parallel, spu- 

 rious branches ; but beyond the middle of the wing spurious and forked branches become 

 alike very closely crowded, oblique, simple branches, which continue along the edge, be- 

 tween the apparent termination of the main vein (about the end of the middle fifth of the 

 wing) and the scapular vein ; in the middle of the wing the area is only about one-tenth 

 the width of the wing. The course of the scapular vein has been described sufficiently 

 under the generic description ; it will be sufficient to add here that there are about half a 

 dozen" longitudinal shoots to the offshoot of the second scapular branch, and that these 

 become more and more closely crowded toward the costal margin ; and that the two prin- 

 cipal branches of the scapular vein originate close together, the second forked at some dis- 

 tance beyond the offshoot. The externomeclian vein is gently arcuate in its basal half. 

 The internomedian vein closely resembles it, and in this particular this species is widely 

 separated from all others ; but it is a little more arcuate, has inferior instead of superior 

 branches, and terminates about the middle of the apical half of the inner margin. The 

 anal furrow is distinct and arcuate, bending downward to the margin more rapidly than 

 usual ; the anal veins are only three in number, crowded close together in the middle of 

 the area, traversing it obliquely, with a slightly sinuous, obliquely longitudinal course. 



The wing is one of the smaller of the medium-sized ones, the fragment measuring 

 19 mm. in extreme length and 8.5 mm. in breadth; it represents a wing of the same 

 median breadth and a length of about 22 mm. ; so that the breadth to the length must 

 have been as 1 : 2.6. The wing' is from the left side. It is marked by a distinct and 

 exceedingly delicate and perfect reticulation of mostly pentagonal cells, two or more rows 

 being seen between the wider interspaces ; but in the narrower ones, as between the closely 

 approximated scapular branches, these are reduced to a single series of tetragonal cells, 

 formed by single, transverse raised lines, as far apart as the interspaces, but still no smaller 

 than the pentagonal cells ; next the border, between the extremities of the mediastinal and 

 scapular veins, these cells form, by the absence of their cross bars, spurious veinlets as 

 long as the apical width of the mediastinal area; between the anal furrow and the nearest 

 internomedian branch they do the same, but the veinlets are longer; and in the apical half 

 of the anal area the same thing occurs on a smaller scale. 



This wing is so peculiar that it can be compared with no other. Germar and Giebel both 

 describe the scapular vein as the mediastinal, and the mediastinal as a delicate, longitu- 

 dinal vein running down the middle of the mediastinal area. 



The single specimen described by Germar was found at Wettin, Germany. Upper car- 

 boniferous. 



Petrablattina nov. gen. (-irpa, Blattina.) 

 Blattina Auct. (pars). 



The mediastinal vein runs parallel to and not very distant from the costal margin (the 

 area occupying perhaps one-fourth of the breadth of the wing), and terminates at some 

 distance beyond the middle of the costal border ; it is abundantly supplied with straight, 



