AMERICAN PALEOZOIC IXSECTS—IIANDLIRSCII. 691 



Order MEGASECOPTERA (Brongniart) Handlirsch. 



In this order I place a series of more highly developed forms, which 

 are derived directly from the Pah\?odictyoptera. These forms are 

 especially distinguished by the fact that a tendency to degeneration 

 appears, name!}", a specialization of the anal part of the wing, as well 

 as a reduction in the number of cross veins, the regular arrangement 

 of these, and the partial coalescence of the media and cubitus w ith the 

 base of the radius. A further important character to be noted is the 

 differentiation of the thoracic segments by the diminution of the 

 prothorax. In agreement with the Paheodictyoptera we here also 

 find 4 equal, horizontal, outspread wings, independent of one another, 

 rather uniform segmentation of the abdomen, and very well-developed 

 cerci. 



I believe that it will not appear too hazardous if I express the opin- 

 ion that the megasecopteres are a lateral branch of the palasodicty- 

 opteres, from which the insects of the panorpatean series have later 

 developed. Various features support this opinion, as, for instance, 

 the cordate head of many Megasecoptera, the independently moving- 

 wings diminished at the base, the approaching cerci of man}^ forms, 

 the reduction of the cross veins, etc. 



The megasecoptera are represented by numerous forms in the mid- 

 dle and upper parts of the Upper Carboniferous of Europe. The lirst 

 two species were discovered in America. 



RHAPHIDIOPSIS Scudder. 



RHAPHIDIOPSIS DIVERSIPENNA Scudder. 



Rhapliidlnpm direrfiipenna Scudder, Bull. U. S. (ieol. Surv., No. 101,189.'!, p. 11, 

 pi. I, figs. e. d. 



Locality. — Cranston, Rhode Island. Pennsylvanian; near l>ase of 

 section; stage? 



This fossil requires further investigation. 



ADIAPHTHARSIA, new genus. 

 ADIAPHTHARSIA FERREA, new species. 



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

 Kittanning(^ (Allegheny) stage. 



An entire insect with horizontally outspread wings. Length of the 

 body (without appendages) 10.2 ram.; length of wing, 8 mm. 



The abdomen is as wide at the base as the thorax, but diminishes 

 posteriorly in a manner similar to that in many megasecopteres. The 

 four wings are similar in form and size, their anterior border is nearly 

 straight, the lower margin strongh- arched, the anal area neither 

 defined nor expanded, Costa, subcosta, and radius are adjacent and 

 nearly parallel; the radial sector appears to emerge about in the mid- 



