S. H. SCUDDER ON PALAEOZOIC COCKROACHES. 51 



this it differs in the simplicity of the branches, which are very rarely furcate ; conse- 

 quently the venation is much more open, and in this respect it approaches Lith. simplex, 

 with which, from its shape, it could not possibly be confounded. 



The single specimen found was obtained by Mr. R. D. Lacoe with the preceding at Port 

 Griffith switch-back, near Pittston, Penn., in the roof shales of the E seam of coal (of Prof. 

 Lesley's table). Upper coal measures of Pennsylvania. 



Lithomylacris simplex nov. sp. PI. 5, fig. 5. 



Fore wing. The wing is long oval, tapering beyond the basal third, but very gradually, 

 the costal margin much arched next the base, the humeral lobe being large and well 

 rounded ; but along the most of its course the costal margin is very gently convex, almost 

 straight in the middle ; inner margin gently convex, the tip tapering but well rounded ; 

 the wing is much broader than in the other species of the genns. The veins originate some- 

 what below the middle of the wing, and curve upward very slowly with a broad arcuation. 

 Mediastinal area occupying more than half the base of the wing, and on the costal margin 

 almost the entire extent of the wing, terminating only a little before the tip ; it is sep- 

 arated from the scapular area by a very gently and broadly arcuate limitation, and is filled 

 with very few veins (only three in the specimen seen), each of which forks once near or at 

 its base ; all are divergent and gently and broadly arcuate, the outer the least so, and all 

 fail to reach the margin. The scapular- vein is very broadly arcuate, running down the 

 middle of the wing parallel to the costal margin, and, finally longitudinal, terminates just 

 beyond (i.e., below) the extreme tip of the wing ; it commences to divide while still arcu- 

 cuate, just beyond the basal fourth of the wing, and emits at subequal distances apart four 

 simple, gently arcuate branches, having a similar direction to the outer mediastinal veins, 

 but if anything less longitudinal. The externoinedian vein, arcuate as far as the division 

 of the scapular, is straight beyond this, parallel to and rather distant from the same, fork- 

 ing simply at the end of the middle third of the Aving, and occupying only an inconsider- 

 able space on the border just below the tip of the wing. The internomedian vein is 

 similar to the preceding at the base, but becomes straight a little sooner and continues 

 straight to the tip, terminating about as far from the apex as the mediastinal vein ; it emits 

 a very short branch close to the tip, another a little beyond the middle of the wing, and 

 two others, which must have their origin much nearer the base, as in the other members 

 of the genus ; only the apical portion of the outer of them, however, can be traced on the 

 specimen. The anal furrow is distinct but not deeply impressed, is very regularly and 

 rather gently arcuate, ami terminates just beyond the middle of the wing, affording a very 

 large anal area. 



The wing is of medium size, measuring probably 24 mm. in length (the fragment is 

 22.5 mm. long) and 10 mm. in breadth at the middle, which is probably not quite so broad 

 as the middle of the basal half of the wing ; or the breadth is to the length as 1 : 2.4. It 

 is nearly perfect, a small portion of the tip only being lost, together with the whole anal 

 area ; it represents a left wing seen from the under surface, the veins being in relief; the 

 veins are prominent, but not remarkably so. and the anal furrow no more prominent than 

 they, if it is as prominent; as in the preceding species, the branches of the internomedian 

 vein are not elevated ; indeed they cannot all be traced in the somewhat worn specimen, 

 and the vein itself, as well as the externoinedian, partakes in part of the obscurity ; this 



