INSECTS OF NEW BRUNSWICK. 31 



known, the carboniferous age of the deposit. Yet we find in this devonian locahty 



not a single one of the Palaeoblattariae or anything resembling them ; and more than 



half the known insects of the carboniferous period belong to that type. The next 



most prevailing carboniferous type is Dictyoneura and its near alhes, with their 



reticulated wings. Gerephemera only, of all the devonian insects, shows any real and 



close af&nity with them ; and even here the details of the wing structure, as shown 



above, are very different. The apical half of the wing of Xenoneura (as I have 



supposed it to be formed) also bears a striking resemblance to the dictyoneuran wing ; 



but the base, which is preserved, and where the more important features lie, is totally 



different. The only other wing which shows particular resemblance to any carboniferous 



form (we must omit Dyscritus from this consideration, as being too imperfect to 



be of any value) is Platephemera, where we find a certain general resemblance 



to Ephemerites Hilckerti Gein., and Acridites prisons Andr., but this is simply in the 



form of the wing and the general course of the nervules ; when we examine the details 



of the neuration more closely we find it altogether different, and the reticulation 



of the wing polygonal and not quadrate as in the carboniferous types.-' In this 



respect indeed, Platephemera differs not only from all modern Ephemeridae, but 



also from those of other geological periods.^ Another prevailing carboniferous type, the 



Termitina, is altogether absent from the devonian. Half a dozen wings, therefore, from 



rocks known to be either devonian or carboniferous, would probably establish their 



age. 



8. The devonian insects were of great size, had meTnhranous wings, and were probably 

 aquatic in early life. The last statement is simply inferred from the fact that all the 

 modern types most nearly allied to them are now aquatic. As to the first, some state- 

 ments have already been made ; their expanse of wing probably varied from 40 to 175 

 mm. and averaged 107 mm. Xenoneura was much smaller than any of the others, its 

 expanse not exceeding four centimetres, while the probable expanse of all the rest was 

 generally more than a decimeter, only Homothetus falling below this figure. Indeed if 

 Xenoneura be omitted, the average expanse of wing was 121 mm., an expanse which 

 might well be compared to that of the Aeschnidae, the largest, as a group, of living 

 Odonata. There is no trace of coriaceous structure in any of the wings, nor in any are 

 there thickened and approximate nervules — one stage of the approach to a coriaceous 

 texture. 



9. Some of the devonian insects are plainly precursors of existing forms, while others 

 seem to have left no trace. The best examples of the former are Platephemera, an 

 aberrant form of an existing family ; and Homothetus, which, while totally different in the 

 combination of its characters from anything known among living or fossil insects, is the 

 only palaeozoic insect possessing that peculiar arrangement of veins found at the base of 

 the wings in Odonata, typified by the arculus, a structure previously known only as early as 



1 Dr. H. B. Geinitz has kindly re-examined Ephemerites ^ The Dictyoneurae and their allies, as may be inferred, 



Ruckerti at my request, and states that the reticulation is in are considered as belonging to the Palaeodictyoptera, 

 general tetragonal, but that at the extreme outer margin although their ephemeridan affinities are not disregarded, 

 the cells appear in a few places to be elliptical five- or six- 

 sided. 



