NO. 233Y. NEW AMERICAN FOSSIL INSECTS— COCKERELL. 305 



PTILOMYLACRIS, new genus (Mylacridae). 



Medium-sized insects with broad subparallel-sided tegmina; sur- 

 face between the veins without visible structure. Costal and radial 

 areas reduced, approximately equal, the radius ending near tho 

 middle of the costal margin. Media greatly expanded, much 

 branched, enclosing ten cells on margin; cubitus long, with nine 

 branches, of which only the eighth is forked; anal area with seven 

 nervures, the lowest forked. 



I have been much perplexed concerning the interpretation of this 

 tegmen, but after close examination in various lights and with 

 different instruments, the above seems correct. The natural ques- 

 tion is, whether all of the apparently extended and complicated 

 media belongs to it, but it seems to do so. The genus is evidently 

 related to Promylacris Scudder and Paromylacris Scudder, both 

 from Mazon Creek, Illinois. 



Type of genus. — Ptilomylaeris medialis, new species. 



PTILOMYLACRIS MEDIALIS, new species. 



Plate 54, flg. 7. 



Length of tegmen about 17.5 mm., Vv^idth 9.5; length of anal area 

 8 mm. ; end of subcosta about 8 mm. from base of wing. Subcost'al 

 branches obliterated; radius apparently very simple, with three sim- 

 ple branches from its upper side (compare Goniomylacris Hand- 

 lirsch) ; media complex, with four branches from upper side, the 

 first two (arising close together) each once forked, the third and 

 fourth each with two simple branches from upper side; cubitus with 

 nine branches, only the eighth forked. The media is not wholly 

 unlike that of Mylacris; it also resembles that of Paromylacris in its 

 general features. 



H olotype.— C&t. No. 64346, U.S.N.M. 



(5) Fragments of another mylacrid species, insufficient for recog- 

 nition 



(6) The following fragment of a tegmen. 



STENOMYLACRIS. species. 



A fragment having exactly the characters of this genus, so far af- 

 the material shows, but the median and radial fields are wholly 

 missing. Subcostal region broad, ordinary for Mylacridae ; branches 

 of cubitus exceedingly oblique and close together, the branching, if 

 any, close to their origin; anal area long and rather narrow (length, 

 10.5 mm.), with numerous veins which form exceedingly acute angles 

 with the margin. The type of Stenomylacris came from the Mam- 

 moth vein. Sharp Mountain Gap, Pennsylvania. 

 3343— 19— Proc.N.M.vol.54 21 



