Scudder — Fossil Insects of North America. 217 



Morris they form the overlying deposit, but a short distance beyond, 

 at Murphysboro, the beds are capped by others and their strati- 

 graphical position made clear. The following section given me by 

 Mr. Lesquereux v^rill afford an idea of their relation to the surround- 



ing strata : — 





/ 

 \ 



1 



The true coal as it occurs in Illinois 





Sandstone 



200 ft. 



Coal 



5 ft. 



Soft blue Shales with pebbles containing Insects, etc. 



40 ft. 



Coal (Morris coal) 



( 3-4 ft. at Morris 

 \ 5 ft. at Murphysboro 



Shales 



40 ft. 



Millstone Grit-conglomerate 



6 ft. 



At Frog Bayou, in Arkansas, the millstone grit is much more 

 extensively developed, and the insect shales lie directly beneath it. 



The fossils at Morris are enclosed in biscuit-shaped ironstone 

 nodules. On weathered surfaces, these nodules show a tendency to 

 lamination, but the interior has a homogeneous, compact structure of 

 a greyish colour ; the enclosed fossil seems to have been the nucleus 

 around which the concretionary action took place.^ The remains 

 consist of reptiles, insects, amphipod crustaceans, worms, and plants. 

 Several insects were found, two of which have been described by 

 Professor Dana'^ under the names of Miamia Bronsoni and Heme- 

 ristia occidentalis. In a letter written to Professor Dana,^ I gave 

 my views of the zoological relations of these animals, and subse- 

 quently published an extensive memoir,* discussing some questions 

 which arose from their study. In both of these insects, the wings 

 were all preserved, and, in one case, the greater portion of the body- 

 also ; but as the wings were embedded in the concretions in their 

 natural position in repose, overlapping one another, new difSculties 

 were added to the determination of their affinities. A close examina- 

 tion of this intricate network of crossed veins enabled me to assign 

 to each wing its respective veins ; the body, also, of Miamia per- 

 mitted restoration. Heretofore no naturalist had made use of the 

 structure of the wings in distinguishing the families of Neurojytera 

 from each other ; but, confident of success, I made careful compari- 

 sons among the living types, and found that characters drawn from 

 these parts were both important and reliable. I showed how a 

 formula of the structure of the wing could be laid down for every 

 family, and thus came to the conclusion that Miamia and Hemerisiia 

 were types each of a new family of Neuroptera, synthetic in character, 



1 Meek and Worthen. Proc. Acad. Natural. Sc. Philad. 1865, pp. 41-2. 



2 Sill. Amer. Journ. Sc. and Arts [2] xxsvii. p. 34. 

 3' Sill. Amer. Journ. Sc. and Arts [2] xl. p. 268. 



4 Memoirs Bost. Soc. Nat. Hist. vol. 1. pp. 173-92, pi. vi. 



VOL. V. — NO. XLVII. 15 



