E. PL. Sellards — Types of Permian Insects. 



?A1 



between the border and the subcosta. It extends, following 

 an arched course, between the subcosta and the border, a distance 

 of two to four millimeters (variable with the different genera), 

 where it divides. The stronger division turns with a uniform 

 curve across the subcosta and ends on the radius, thus forming 

 the brace. The weaker division turns upward, reaching to and 

 quickly joining the costal border. This structure is also seen 

 in the wings of many modern Ephemerid genera, where it is 

 apparently a disappearing character. As a convenience of 

 reference I suggest for this structure the term Costal brace. 



Fig. 3. Type specimen of the genus Protereisma. Head, thorax, and first 

 seven segments of the abdomen preserved. The wings are preserved com- 

 plete except at the tips. The wings are thin and flat. The venation is made 

 more indistinct by the fact that the four wings lie together. The dotted 

 veins and the tips of the wings restored from a second specimen of the same 

 species. Enlarged 4 times. 



Protereisma gen. n. 



The genus Protereisma* is regarded as the type genus of 

 the family. The wings are thin, elongate, and but slightly 

 corrugated. The costal border is straight, the inner border 

 rounded. The greatest width is near the middle line of the 

 wing. The venation conforms to the type described for the 

 family. The middle vein of the sets of three arises from the 

 upper division. This feature together with the but slightly 

 corrugated membrane gives a more lax appearance to the wing 

 * Protos, first ; Ereisma, brace. 



