56 S. H. SCUDDER ON PALAEOZOIC COCKROACHES. 



arity of the mediastinal vein is of special interest as showing a certain affinity to the 

 Blattinariae, next which it is here placed; yet the distribution of the branches is never- 

 theless radiate, and the form of the area triangular and not band-shaped, according in this 

 respect wholly with the Mylacridae. It should be taken as the type of Necymylacris, for the 

 imperfection of the preceding species renders its alliance with this somewhat doubtful. 



The single specimen, which I owe to the kindness of Mr. I. F. Mansfield, was obtained 

 by him at Cannelton, Beaver Co., Penn., in a dark sandy shale immediately under the vein 

 of cannel coal known as vein C of Professor Lesley. Lower coal measures of Pennsylvania. 



Blattinariae. 



In the second group into which the palaeozoic cockroaches may be divided, the medi- 

 astinal vein is not constructed like the anal vein, but like the other veins of the wing, 

 being composed of a main vein which extends at least half way to, usually some way 

 beyond, and sometimes quite to, the tip of the wing, emitting toward the costal border 

 several branches which are usually subequal, equidistant and parallel, often forking once in 

 some part of their course, the apical branches occasionally many-branched. The area 

 covered by this vein and its branches is thus band-shaped, and terminates beyond the 

 middle of the wing. The group occurs both in Europe and America, all of the European 

 and somewhat less than half of the American species falling therein. The wings as a 

 general rule are slenderer than those of most of the Mylacridae, the breadth being- 

 contained in the length on an average more than two and a half times. 



o 



Etoblattina (i'rus, Blattina) nov. gen. 



Blattina Auct (pars). 



The mediastinal vein of the fore wings with its branches covers a rather narrow and not 

 very extended area, being seldom more, seldom much less than one-fourth of the width of 

 the wing, and generally terminating apically from a little more than one-half to a little 

 less than two-thirds the distance toward the tip of the wing ; in one or two instances, as 

 particularly in E. leptophlebica, it extends a little more than two-thirds the distance ; the 

 area is usually of uniform width nearly to the tip, but it sometimes tapers throughout the 

 entire apical half, and in E. jjrimaeva, where the whole wing is very broad, it tapers with 

 unusual rapidity and throughout the greater part of the wing; the principal vein emits 

 from five to ten simple or forked, equidistant, oblique branches. The scapular vein gen- 

 erally terminates just before the tip of the wing, rarely at the tip itself, and occasionally is 

 decidedly removed from the tip, though not to a great distance ; it generally begins to fork 

 a little before the middle of the wing, occasionally at it, and rather more frequently only 

 one-third the distance from the base ; and the branches usually take on the mode of distri- 

 bution of those of the mediastinal vein, although the similarity is sometimes lost from the 

 greater breadth of the area and the consequently greater length of the veins; in other 

 instances, and particularly in those in which the early branching of this vein is correlated 

 with more than an average length in the mediastinal area (as particularly in E. venusta), 

 all similarity is lost, the division assuming more or less of an arborescent form, generally 

 accompanied by frequent ramifications; as a general rule, however, more or less similarity 

 exists between the two areas, and in some (as in E. affinis, E. Dohrnii) the resemblance is 



