S. H. SCUDDER ON PALAEOZOIC COCKROACHES. 43 



Mylacris Heeri. PI. 5, fig. 11. 



Blatthia Heeri Scudtl., Can. Nat., vu, 272, fig. 2. Figured also in Dawson's Acadian 



Geology, Suppl. to 2d ed., p. 55, fig. 6. 



Fore wing. The tip of the only specimen known is broken so that the exact form 

 cannot be stated, but the wing was probably a little more than twice as long as broad ; the 

 costal margin is regularly and moderately convex, perhaps a little flattened in the middle ; 

 the base of the inner margin is nearly straight. The veins originate from a point a very 

 little below the middle of the wing, and having scarcely the least upward curve at base are 

 nearly straight. The mediastinal area is very large, regularly triangular, with only a few 

 distant straight very gently diverging veins; in the specimen before me there are four 

 veins, of which the lowest is forked almost at the base and the second in the middle ; almost 

 the entire costal edge preserved is covered by this area and it probably covered two thirds 

 of the wing along this border, and occupied fully half the breadth of the wing at base. 

 The scapular vein is very gently sinuous, being curved slightly downward close to the base 

 and upward toward the tip, the intervening portion being straight and passing exactly 

 down the middle line of the wing ; the branches, four in number, are straight, equidistant, 

 parallel to the nearer mediastinal veins, only the basal one (which originates very near the 

 base) being forked and that close to the tip ; the vein itself, judging from its apical direction, 

 terminates just before the tip, leaving at the margin a very narrow field for this area. The 

 externomedian vein is straight and forks probably at the middle of the wing ; how many 

 times it forks is uncertain, two branches only being present in the fragment ; the area must 

 occupy the whole of the apex of the wing. The internomedian vein is also remarkably 

 straight, having only the slightest curve at the extreme base and probably terminating 

 just as far before the tip as the scapular vein; it emits, in the fragment preserved, three 

 rather closely approximated branches, the outer more longitudinal than the others and 

 forked; from the course of the upper branch of this fork (not represented as sufficiently 

 longitudinal in the plate) and from the absence of other primary branches from the apical 

 portion of the main stem which is preserved, it is probable that this secondary branch runs 

 parallel to the main stem and that the outer branches are emitted from it, as in the 

 preceding species. In keeping with the straightness of the other veins, the anal furrow is 

 exceptionally straight ; it is deeply impressed only over its basal half and is very gently 

 and equally curved throughout, terminating probably at about the middle of the posterior 

 border ; the anal veins are five or six in number, most of them forked near the middle, the 

 innermost compound, and the outer more closely approximated than the others ; all of them 

 are straight beyond a frequently curved base. 



The species is a tolerably large one, the fragment of the wing being 21 mm. long (its 

 probable entire length about 25-26 mm.) and its breadth 11.8 mm., or the breadth to the 

 length as 1 : 2.1. The veins and their branches are rather distinctly impressed, somewhat 

 distant and regular; the interspaces are transversely and very faintly wrinkled, rather 

 than provided with cross-nervulcs ; the surface is nevertheless pretty smooth ; the costal 

 margin is very delicately marginate. The tip of the wing is broken off. so that from 

 a fourth to a fifth is gone, but the fracture extends much further down the inner margin, 

 extending even onto the anal area. 



