SPECIES OF MYLACRIS. 301 



area is very largo, the anal furrow being very pronounced, broadly curved and extending 

 far outward in a somewhat unusually longitudinal course nearly to the middle of the wing; 

 the anal veins appear to belong to two sets opposed to each other, an upper with inferior, 

 and a lower with superior branches, all very longitudinal, nearly parallel with the costal 

 margin and nearly all simple ; the upper area is just as longitudinal as the lower and quite 

 independant of the course of the furrow, leaving a huge sub-triangular space near the 

 most strongly curved portion of the furrow quite devoid of veins. 



The species is a very large one, the largest of the genus yet known ; the fragment of 

 the wing being 33 mm. long (its probable entire length 37 mm.) and its breadth about 

 17.5 nun. ; or, the breadth to the length as about 1 : 2.1. All the veins are in very dis- 

 tinct relief, with the interspaces deeply sunken between them ; there seem to be no 

 surface markings. The specimen is curiously preserved, the edge of one-half of the 

 nodule falling longitudinally across the inner margin, following nearly the mid-space be- 

 tween the two sots of anal veins as marked by the light belt in the larger figure we shall 

 here: Iter give; all the parts below this, together with the opposite left wing (given in the 

 other figure) lie over the v<\ix^' on the back side of the stone, the plane of which lies at 

 an angle of about 45° with that showing the main portion of the right wing, and forms the 



O O XT O O 7 



present surface of the nodule ; the other half of the nodule shows the counterpart of our 

 larger figure. 



This species is, as we have said, most nearly allied to M. Uteri in the great amount of 

 space occupied by the mediastinal and scapular area- as well as by the course of the anal 

 furrow, and apparently by the peculiarities of the anal veins. It is. however, a very much 

 larger species than it (or any other species of Mylacris), and the peculiar dichotomous 

 division of the scapular vein separates it at once from every species known, and it is nearly 

 as peculiar for the longitudinal course and sinuous sweep of the internomedian vein-. In 

 the general positions occupied by the different areas, it resembles M. lucifugum, with which 

 it better agrees in size ; hut it disagrees with it, not only in the peculiar division of the 

 scapular vein, but in the less crowded and more regular veins of the mediastinal area, and 

 the more rounded humeral lobe. 



The specimen comes from the famous locality of Mazon Creek, and is in the collection of 

 Mr. R. D. Lacoe under the number 2036. Having been received after the plate was en- 

 graved, figures of the species will be given on some future occasion. 



4. Mylacris lucifugum nov. sp. 

 PL 27, fig. s. 



Front wing. The basal portion, excepting the anal area, is preserved, but at least the 

 apical third is gone. There is a rectangular rounded shoulder of considerable extent, 

 minutely margin ite, but without neuration ; the basal, preserved half of the costal mar- 

 gin is straight, but at the extremity of the fragment begins to curve slightly, and this 

 with the direction of the vein- makes it probable that beyond this it was gently arcuate, 

 the tip rounded and the inner margin nearly straight. The mediastinal veins are confused 

 at their base by vegetable remains and may be inaccurately given in the plate, but they 

 apparently occupy the area marked, or more than one-third of the fragment and nearly 



