114 S. H. Scudder— Devonian Insects. 
the Termitina, is altogether absent from the Devonian. Half 
a dozen wings, therefore, from rocks known to be either De- 
vonian or Carboniferous, would probably establish their age. 
8. The Devonian insects were of great size, had membranous 
wings, and were probably aquatic in early life. The last state- 
_ ment is simply late from the fact that all the modern types 
most nearly allied to them are now a As to the first, 
some statements ae already been made;, their expanse of 
hg pats eae from 40 to 175 mm. ae averaged 107 
oneura was much smaller than any of the others, its 
acrianie 6 aheoediic four centimeters, while the probable 
we gt of all the rest was generally more than a decimeter, 
only Homothetus falling below this te ure. Indeed if Xeno- 
neura be omitted, the average expanse of wing was 121 mm., 
is no trace of coriaceous structure in any of the wings, nor in 
any are there thickened and ea nervules—one stage 
of the approach to a coriaceous textu 
9. Some of the Devonian insects are plainly precursors be 
existing ee while others seem to have left no trace 
examples of the former are Platephemera, an aberrant form “a 
an aximing family ; and Homothetus, which, while totally dif 
ferent in the combination of its characters from anything 
possess ; pr Ranoenite: where the fethoseretal of the inter- 
nomedian branches to each other and to the rest of the wing is 
altogether abnormal. If too, the concentric Tidges, formerly 
repented even in any modified form 
ey show a remarkable variely of structure, vase an 
coc of insect life at that epoch. This is s the more notice- 
able from their belonging to a single type of wis, a stated 
under the seventh head, where we “have seen that their neura- 
tion does not accord with the commoner type of wing structure 
found in Paleozoic insects.* These six wings exhibit a diver: 
sity of neuration quite as great as is found among the hundred 
or more species of the Garhontteicus epoch; in some, such as 
* Cf. Mem. Bost. Soc. Nat. Hist., iii, 19, note 1. 
