222 Sellards — Structure of Paleozoic Cockroaches, 



venation of the hind wing of the Mylacridse. The wing is 

 narrowed at the base, the costal border being nearly straight or 

 a little concave at this point. The inner border although not 

 complete is evidently rounded, and the apex obtuse. The 

 most interesting feature of the wing is the position of the 

 costa, which is some distance from the margin and gives off a 

 thin superior branch. The subcosta is a stronger vein, but has 

 only one offshoot. The radius is more developed ; it divides 

 into two nearly equal parts near the base, both of which are 

 compound, the ultimate divisions supplying the border from 

 the termination of the costa to the apex. The media also 

 divides into two compound, nearly equal divisions close to the 

 base, the branches running to the apical border. The cubitus 

 gives off a few inferior branches which curve regularly to the 

 border. Only a small part of the anal area is preserved. The 

 wing just described is the left wing of the specimen. The 

 costa of the right has two thin superior branches. The radius 

 differs in the detail of its branching; the first and second off- 

 shoots of the lower division of the main vein are united for a 

 short distance at their base, making a single forked branch 

 instead of two simple branches. Length of the wing, 24 or 

 25 mm ; breadth, 11 or 12 mr \ 



Formation and Locality. — Middle or Lower Coal Measures, 

 Mazon Creek, Illinois. 



The type of hind wing most abundant in the Lawrence Shales 

 is that illustrated in Figure 33. There are nine specimens of 

 the species, all conforming closely to a common type. The wings 

 are uniformly ovate. The inner border is full and rounded. 

 The costa is straight, simple, and reaches about one-fourth the 

 length of the wing. The subcostal area is, as usual, in the hind 

 wing, narrow and of slight extent. A few thin superior 

 branches are given off from the main vein beyond the extrem- 

 ity of the costa. The radial area reaches nearly to the apex 

 and has about four forked branches. The median area is large 

 and fills the apex. The cubitus has several very oblique, sim- 

 ple, parallel branches. The few anal veins are parallel and 

 usually simple, longer and more curved than in Spiloblattina 

 maledicta. The wings are all of a brownish color. The 

 species doubtless belongs to the genus Etoblattina, as the 

 wings are of the ovate type, with full inner borders, thus resem- 

 bling other species of that genus. Length of wing, 1 8 to 20 mm ; 

 width, 9 to ll mm . 



Formation and Locality. — Upper Coal Measures, Lawrence, 

 Kansas. 



Another species, the generic reference of which is doubtful, 

 is represented by three specimens. The wing is contracted at 

 the base and has an unusuallv narrow attachment. The costal 





