IX. New Types of Cockroaches from the Carboniferous Deposits 



OF THE United States. 



By Samuel H. Scudder. . 



Read May 7, 1890. 



OliSrCE the publication of my revision of the carboniferous cockroaches of the world, 

 a very considerable number of new forms have been described from the Old World and 

 a good many additional kinds have been found in our own country. A few of these 

 from the Eichmond, Ohio, coal fields have been described by me, and a very large num- 

 ber more are in my hands awaiting investigation. The forms herewith described (for 

 the first time in full) have been awaiting an opportunity for illustration before final pub- 

 lication, and extend considerably our knowledge of the ancient fauna, several of the spe- 

 cies showing much more than the upper wings, upon which we have heretofore mainly 

 depended. The larger part of them come from Mazon Creek, 111. 



MYLACRIDAE Scudder. 



As there are two generic forms to add to the three published in my paper on Palaeo- 

 zoic cockroaches, I add a new table of the genera of this family. 



table OF the genera OF MYLACRIDAE. 



AU the branches of the mediastinal vein arising close to the base of the wing. 

 Mediastinal and scapular areas together occupying less than half the wing. 



Scapular area larger than the mediastinal Mylacris. 



Scapular area smaller than the mediastinal Promylacris. 



Mediastinal and scapular areas together occupying lialf or more than half the wing. 



Wings broad; externomedian area expanding apically Paromylacris. 



Wings narrow ; externomedian area small and compressed, scarcely expanding apically . Lithomylacris. 



A number of tlie apical branches of the mediastinal vein arising beyond the base of the wing and scarcely partakinii of 



the radiate arrangement of the others Necymyla oris 



Mylacris mansfieldii. 



Mtjlacris mansfieldii Scudd., Mem. Bost. Soc. ISTat. Hist., in, 47 (1879). 



A fragmentary and small specimen of this species, affording some points in addition 



MEMOIRS BOSTON SOC. NAT. HIST., VOL. IV. 64 (401) 



