SPECIES OF MYLACRIS 307 



of the space, the interne-median first forks between the first and second branches of the 

 scapular, while in 31. pennsylvanicum only opposite the base of the third branch ; the anal 

 veins are also much more numerous in the present species. 



7. Mylacris anthracophilum. 



Mylacris anthracophilum Scudd., in Worth.. Geol. Surv. 111., in, 568-570, figs. 5, 6. — 

 lb., Mem. Bost. Soc. Nat. Hist., in; 45-47, pi. 5, figs. 6-8. 

 Colchester, 111. 



8. Mylacris priscovolans 



PI. 27, fig. 9. 



Fore-wing. A bit of the extreme tip and a considerable part of the wing next the inner 

 border is wanting, although the position of the margin itself is indicated by a depressed 

 line upon the stone, showing the form of the wing to have closely resembled that of 31. 

 carbonum, being broadest at the extreme base, narrowing toward the apex with increasing 

 rapidity, so that the inner margin being straight, the costal margin is considerably curved ; 

 the tip, though narrow, is broadly rounded, and lies within the median line of the wing ; the 

 humeral lobe is very square, rounded only at the extreme angle. The mediastinal area is 

 of a very regularly triangular form, one-third the width of the wing at the base, and apically 

 extending considerably beyond the middle of the distal half of the wing ; its three or four 

 veins fork near the base, and extend their long, simple, or branching rays far out to the 

 margin. The scapular vein is rather strongly curved near the base, beyond which it 

 sweeps with a very slight opposite arcuation, subparallel to the costal margin to the very 

 tip of the wing; its four or five long and mostly simply and deeply forked branches have 

 a completely longitudinal course, and the area forms a triangle of about the same size and 

 regularity as the mediastinal area, but with an opposite disposition. The externomedian 

 vein passes with a curve similar to, but stronger than that of, the scapular vein, diverging 

 from it, and terminating on the inner margin beyond the middle of the outer half of the 

 wing ; but within the extremity of the mediastinal vein, its long, arcuate, simple, or simply 

 forked branches being superior. The internomedian vein is again curved in the same sense 

 as the externomedian and has about four simple or forked arcuate branches. The anal 

 furrow starting from above the middle of the wing is deeply impressed, regularly and con- 

 siderably arcuate, but more strongly curved in its basal than its apical half, and terminates 

 at the middle of the inner margin ; the anal veins are oblique or arcuate, simply forked 

 or compound, somewhat irregular and hardly more crowded than the internomedian veins. 



The species is a large one, the wing measuring 26.5 mm. in length by 14.5 mm. in 

 breadth, the breadth being to the length as 1 : 1.8 ; the continuous part of the fragment is 

 25 mm. long and 12 mm. broad at the base. The wing is a right one, the under surface 

 (or cast of the upper) having been figured, and the veins are distinctly and sharply 

 impressed ; no sign of cross venation or of any reticulation appears. The wing is peculiar 

 for its excessive breadth at base combined with its square-shaped humeral lobe, which causes 

 it to taper from the very base ; it is nearly allied to 31. carbonum and 31. anthracophi- 

 lum, differing from both in the peculiarities just noted, as well as in the less produced and 



