INSECTS OF NEW BRUNSWICK. , 29 



with the scapular vein, there is also nothing to separate it from the Sialina, excepting their 

 amalgamation for so great a distance ; but the structure of all the other veins and the 

 peculiarities of the cross venation is very different from the same points in the Sialina. 



In the course of most of the main veins and their mode of branching, it has some 

 resemblance to the Raphidiidae, but it has no afl&nity whatever with that group in the 

 peculiar directions of the nervules and their connection by distant cross veins, so as to 

 form large polygonal cells, which is one of the most striking of the characteristic features 

 of Raphidiidae. 



The apical two-thirds of the wing (excluding, therefore, the attachments of most of the 

 veins) are in sufficient harmony with these parts in the carboniferous Dictyoneurae to 

 presume, at first, that the wing will fall in the ancient order of Palaeodictyoptera. As yet, 

 however, we know too little of the extent and even of the peculiar characteristics of this 

 group to say whether or not the structure of the base of the wing will allow its location 

 here ; certainly it will not admit its being placed in the same family with the genus Dictyo- 

 neura ; and at present this is, perhaps, all that we can say vmtil the structure of aU the 

 ancient wings shall have been most carefully studied. 



It is in large measure in those points of structure which Dictyoneura shares with the 

 Ephemeridae, that Xenoneura is comparable to the former, and we therefore see in this 

 wing ephemeridan, sialidan, raphidian and coniopterygidan features, combined with others 

 peculiar to itself. Whatever the closest affinities of the wing may prove to be, it must 

 certainly, by its combination of characters, bridge over the gulf now separating the wing 

 features of Neuroptera and Pseudoneuroptera ; and these various considerations assure us 

 of its family distinction from any known ancient or modern type of Neuroptera, and of 

 the propriety of applying to the group it represents the family name of Xenoneuridae. 



This species, with Gerephemera simplex, came from the lowest insect-producing beds of 

 the Lancaster Shales, called plant bed No. 2, by Professor Hartt. 



IX. Geneeal Summary. 



It only remains to sum up the results of this re-examination of the devonian insects, 

 and especially to discuss their relation to later or now existing types. This may best be 

 done by a separate consideration of the following points : 



1. There is nothing in the structure of these earliest known insects to interfere with a 

 former conclusion ^ that the general type of wing structure has remained unaltered from 

 the earliest times. Three of these six insects (Gerephemera, Homothetus and Xenoneura) 

 have been shown to possess a very peculiar neuration, dissimilar from both carboniferous and 

 modern types. As will also be shown under the tenth head, the dissimilarity of structure 

 of all the devonian insects is much greater than would be anticipated ; yet all the features 

 of neuration can be brought into perfect harmony with the system laid down by Heet. 



2. These earliest insects were hexapods, and as far as the record goes preceded in time 

 both arachnids and myriapods. This is shown only by the wings, which in all known 

 msects belong only to hexapods, and in the nature of things prove the earher apparition 

 of that group. This, however, is so improbable on any hypothesis, that we must conclude 

 the record to be defective. 



iThe early types of insects. Mem. Bost. Soc. Nat. Hist., Ill, 21. 



