50 S. II. SCUDDER ON PALAEOZOIC COCKROACHES. 



This species, like the next, is peculiar for the division of the internomedian vein, 

 which, excepting for a small apical fork, emits all its branches near the base ; in shape 

 it closely resembles that species, even to the flatness of the internomedian area; but 

 it differs from it in its greater length, the greater frequency of the branches, and their 

 much more abundant forking, especially in the externomedian vein, which also divides 

 much nearer the base in this species than in IAik. pittstonianum. The shape of the wing 

 and the closer venation at once separates this species from LUh. sulcatum. 



The single specimen was found with the following species by Mr. R. D. Lacoe, at Port 

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

 Second Pennsylvania Survey, and by him forwarded to me for examination. Upper coal 

 measures of Pennsylvania. 



Lithomylacris pittstonianum nov. sp. PI. 5, figs. 4, 10. 



Fore wing. The single specimen known is very imperfect, the base, anal area, and a 

 large part, of the tip being lost,* and the remainder badly fractured ; it is evident, however, 

 that the wing is very long and slender, with a gently and regularly arcuate costal margin ; 

 probably the wing is nearly equal, tapering very gently on the apical half. The veins 

 must originate below the middle of the wing, and are nearly straight. The mediastinal 

 area, which is more than half the width of the wing at the base, terminates at the middle 

 of the costal margin, and is separated from the scapular area by a straight border, the 

 veins, six or seven in number, being straight, gently divergent, and simple or rarely con- 

 nected close to the base. The scapular vein runs parallel to the costal margin in the basal 

 half of the wing, gradually approaches it in the apical half, and terminates probably a little 

 before the tip ; it emits five simple, straight, branches, which divaricate very slightly in 

 continuation of the divergence of the mediastinal veins, which they entirely resemble ; the 

 mediastinal and scapular areas together occupy just about one half of the wing. The 

 externomedian runs parallel to the scapular vein, divides a little beyond the middle of the 

 wing, and emits about four inferior, slightly arcuate branches, which are simple (unless the 

 first be apically forked), and together probably occupy the entire apical margin of the 

 wing. The internomedian vein is very gently arcuate, and must terminate just before 

 the tip of the wing ; it emits, wholly in the basal third of the wing, three simple or simply 

 forked branches which are very longitudinal. The anal furrow is distinctly but not heavily 

 impressed, very gently arcuate, and must terminate at about the end of the basal third of 

 the wing ; but such is the slenderness of the wing and the low origin of the principal veins, 

 that the anal area must be several times longer than broad. 



The wing is of moderate size, the fragment measuring 22.5 mm. in length and 8.5 nun. 

 in breadth ; probably the entire length of the wing is 26 mm., or the breadth to the length 

 as 1:3; it is a left wing with the upper surface exposed ; the veins are all very distinctly 

 impressed, excepting those of the internomedian area, which are obscure ; the interspaces 

 between the veins are vaulted also, so as to add to the impression of the veins themselves ; 

 but otherwise it is smooth excepting in the flatter internomedian area, where a delicate 

 and crowded cross-veining is faintly marked ; the basal third of the costal edge is gently 

 margined. 



With the preceding species, this insect is peculiar for the basal attachment of the 

 internomedian branches. In its shape it resembles only Lith. sulcatum in this genus ; from 



