AMERICAN I'ALEOZOR ' INSECTS— HA NDLIRSCH. 



693 



spaces arc l>ridged over by strai(»'ht cross veins far removed from each 

 other. The wing's are not horizontally outspread, as in previously men- 

 tioned forms, but are laid back Hat over the abdomen, yet not folded. 



The derivation of this form from the pala^odictyopteres is certaiidy 

 not so difficult as the determination of its relations to the more highly 

 developed groups, of which, in my opinion, the highest perlids and 

 embids come into consideration. In view of the entire course of 

 ev^olution, the latter of these groups seems to me to agree most closely, 

 on account of the stronger reduction of the anal portion of the wing 

 and of the cross veins, for it must be admitted that the progenitors of 

 the perlids may also have already possessed a tendency to the forma- 

 tion of an anal fan in the hind wing; further, that the number of their 

 longitudinal and cross veins may have been still greater. If the 

 reduction of the cross and longitudinal veins in the wing of Hadento- 

 v'tiim is imagined to have advanced only a little farther, there would 

 result in any event an embidlike form of wing. 



This explanation, however, still remains very uncertain, and it is 

 easily possible that direct descendants of Iladentoinuin no longer exist. 



HADENTOMUM, new genus. 

 HADENTOMUM AMERICANUM, new species. 



Locality. — Mazon Creek, near Morris, Illinois. Pennsylvaiiian; 

 Kittanning? (Allegheny) stage. 



A, /. 



Figs. 19, 20, 21.— Hadentomum american'um. 



Length of front wing, 20 mm, ; length of entire specimen 35 mm. 

 Daniels collection. Reverse of cot^^pe in the U. S. National Museum : 

 Cat. No. 35579. 



