SPECIES OF MYLACRIS. 305 



the fragment has three simple slightly curved branches, their convexities toward the anal 

 area, and their bases considerably further apart than the scapular branches. The interno- 

 median runs parallel and close to the externomedian vein and its basal branch, probably 

 reaching the inner margin more than half-way from the anal furrow to the apex ; it com- 

 mences to divide as soon as there is space for it opposite the middle of the anal furrow, 

 the first branch forking, and the second branch originating, next the first branch of the 



O 7 DO 7 



externomedian vein ; a third branch springs at a similar distance further on, but more 

 cannot be seen. The anal furrow is tolerably distinct, curved gently throughout and bent 

 a little in the middle, terminating at mor%than one-third of the distance toward the tip, 

 or about opposite the first divarication of the externomedian vein ; the anal veins are 

 exceedingly numerous and crowded, many of them forked, some of them doubly, gener- 

 ally near the middle of their course ; those next the anal area are obliterated, but if they 

 retained the character of the remaining part of the area, about twenty veinlets must have 

 impinged upon the outer margin in the anal area ; those lying next the angle of the wing 

 have a sinuous course, changing to a simple gently arcuate curve toward the anal furrow. 



This fragment represents a species of tolerably large size, the breadth of the wing 

 being 13.5 mm., the length of the fragment 23 mm., and the preserved length of the wing 

 about 27 mm. ; so that the breadth to the length must have been as 1:2. It is the under 

 surface of a right wing, all the veins and the anal furrow being in relief and, with the 

 exception of the anal veins and the internomedian branches, somewhat prominent. No 

 trace of reticulation or transverse wrinkling can be seen. 



The specimen occurs on a piece of black carbonaceous shale with reeds at Cannelton, 

 Penn., and was sent me by Mr. R. D. Lacoe with the number 2022 a. 



After the above description was prepared two other specimens came into my hands 

 through the indefatigable exertions of the same friend. As they are less perfect than 

 that already described, the points in which they vary from it may best be pointed out by 

 separate description. 



The first, No. 2022 b, c, occurs in duplicate on the same stones with No. 2024, M. 

 pennsylvanieum, and was found at Cannelton, Penn., in the same shales as that which 

 yielded the type. It preserves a middle fragment of the wing, with a portion of the costal 

 margin only, and a minute bit of the inner margin ; no part of the wing appears which 

 is not seen in the type, unless it be a little more of the externomedian vein. It is a little 

 smaller than that specimen, its width at the end of the basal third of the wing being 11 

 mm., where in the other specimen it is fully 13 mm. In 2022 b, c, all the mediastinal 

 veins are straight and simple as far as they can be seen, so that they do not divide beyond 

 the base, giving this area a very different appearance from what it has in 2022 a. The 

 scapular vein, although extending on the fragment as far toward the apex as in 2022 a, 

 has only three branches, the outer two simple so far as they can be seen, the basal, how- 

 ever, dividing at its very base into two forked branches, the upper fork of the upper branch 

 again dividing ; this is somewhat different in description from the condition in 2022 a, 

 but is really much the same as if the second offshoot of the first branch were united to the 

 first offshoot and they together arose in the axilla of the first branch. The externome- 

 dian vein also differs somewhat and reminds one rather of the arrangement of that vein 



