44 S. H. SCUDDER ON PALAEOZOIC COCKROACHES. 



The course of the anal furrow separates this species from all others of the genus. 

 In the structure of the internomedian vein, but in hardly any other special feature, it 

 is allied to Myl. bretonense. In the general distribution of nearly all the veins it is very 

 nearly related to Myl. pennsylvanicum, a slightly larger or at any rate a broader species; 

 indeed these two species are more closely related than any other two American forms; 

 but the slight curvature and consequently great length of the anal furrow of this species 

 forbid their being considered the same, and this differs also from the other in the less 

 crowded neuration of all parts of the wing, in the less sinuous course of the scapular vein, 

 and in many other minor points. 



The single specimen occurred on dark grey shale, associated with ferns and leaves 

 of Spkenophyllum Schlotheimii, and was found, with the preceding species, in the produc- 

 tive coal measures (or middle coal formation) of Sydney, Cape Breton, by Mr. Richard 

 Brown, F. G. S., and communicated to me by Principal Dawson. 



Mylacris pennsylvanicum now sp. PI. 5, figs. 13, 14. 



Fore wing. Only the basal half of the wing is preserved, with none of the inner margin, 

 so that it is impossible to determine the form of the wing ; the course of the veins however 

 would seem to indicate a shorter and stouter, as it certainly is a broader wing than in Myl. 

 Heeri. The outline as given in fig. 14 probably makes the wing a little too long. The 

 costal margin is regularly and considerably convex, more so than in Myl. Heeri. The 

 veins originate from the middle of the wing or slightly below it, and curve a little at the 

 base. The mediastinal area has a basal width of half the wing and, separated from the 

 scapular by a scarcely curved line, strikes the costal margin close to the limit of the frag- 

 ment, and probably somewhat, perhaps considerably, past the middle of the wing; the 

 extreme base is covered in the specimen by a foreign object, but four veins appear beyond 

 it, 1 the two middle ones simple, the others deeply forked, all tolerably close, scarcely 

 divergent, oblique and very gentry arcuate ; toward the humeral angle there are no veins 

 and the edge of the wing at this point is very narrowly and delicately marginate. The 

 scapular vein is gently and broadly sinuous throughout and probably terminates before the 

 apex of the wing, to judge from its apical curve; it runs very closely parallel to the costal 

 margin through most of its course, and down very nearly the middle line of the wing, 

 perhaps nearer the costal than the inner margin ; it commences to divide very near the 

 base and emits five branches, all but .the first of which are simple and all are subparallel to 

 the course of the outer mediastinal veins; the basal branch is doubly forked and renders 

 this portion of the area a little more crowded. The externomedian vein is arcuate until it 

 divides, before the middle of the wing certainly, and some distance before the extremity of 

 the fragment; it forks only once however in the part preserved, two parallel veins running 

 longitudinally to the edge, equidistant from each other and the veins on either side. The 

 internomedian vein runs in a broadly sinuous course parallel to the preceding vein, and 

 although much obscured upon the specimen, at least one and perhaps two branches can be 

 seen to be emitted before the division of the externomedian vein. The anal furrow 

 is strongly impressed upon its basal half, less so but still distinctly upon the apical half, 

 appears to be composed of a pair of fine grooves closely approximated, and is regularly 

 and not very strongly arcuate, terminating on the inner border at some distance before the 



1 In both the figures on our plate the vein nearest the humeral angle should be erased; it does not exist. 



