HEMIPTERA—HOMOPTEKA— APHIDES. 249 



origin, but apparently arising four times as far from the second oblique as 

 the second from the first ; it forks at somewhat less than half-way to the 

 hind border and runs by a series of bends at a long distance below the 

 middle of its area, forking a second time nearly as far from the first as 

 the first from its root. The stigmatic vein is arcuate and diverges rather 

 widely from the stigma, but the length of the stigmatic cell can not be 

 determined. 



Length of fragment, 3.5°""; probable length of wing 4.4""°; breadth, 

 1.4"™. 



Named for Prof William Morris Davis, of Harvard College. 



Florissant. One specimen, No. 14053. 



2. GrERANCHON PKTRORUM. 



PI. 2, Fig. 6. 



Laehnus petrorum Scudd., Rep. Progr. Geol. Surv. Can., 1675-'76, 279 (1877). 



A fragment of a wing is sufficiently preserved to show that it should be 

 referred here, while the exact position of the veins is difierent from that of 

 the other species. The wing is unusually slender ; the postcostal vein thick- 

 ens apically as it merges in the stigma ; the first oblique vein is straight ; 

 the second originates very close to the first, runs parallel to it only at the 

 very base, and then bends pretty strongly outward, striking the margin of 

 the wing nearly as far from the tip of the first oblique vein as half its own 

 length ; the origin of the cubital vein is not clear, but it is apparently not 

 far out, in which case it runs parallel with the second oblique vein until it 

 branches in the middle of the wing ; the lower of these branches almost re- 

 tains the course of the basal part of the veins, but diverges slightly from the 

 second oblique vein, terminating very far from it on the border of the wing ; 

 the main stem, diverging from the first branch rather widely at first, almost 

 at once runs parallel to the lower branch, and when it has continued a less 

 distance than the main vein before its furcation, divides, the two forks di- 

 verging but slightly at base, and then very gradually converging until they 

 are no farther apart than the bases of the first and second oblique veins, and 

 the upper fork almost touches the stigmatic vein (probably by some dis- 

 placement) ; together they diverge a little from the lower branch of the 

 cubital vein ; the stigmatic vein is very conspicuous, passing by a broad 

 sweep into the heart of the wing, diverging from the stigma at a greater 



