MUSEUM OF COMPARATIVE ZOOLOGY. 281 
Dyscritus vetustus. 
A very small fragment, said to belong to the hind margin of a wing, with two 
series of eight square-shaped cells between three veins, one of them branched 
at the base, is all that is preserved. It can belong to Orthoptera, to Pseudo- 
neuroptera, or to Neuroptera, but it is too insignificant to be identified. Simi- 
lar cells are found in Isophlebia. 
The conclusions to be made from the results of my examination of the 
Devonian Insects are the following : — 
1. The known fragments belong to five species. 
Two are Odonata, belonging to the Pseudoneuroptera. The very im- 
perfect fragments do not permit us to say more than that some charac- 
ters are similarly represented in the gigantic species of the Solenhofen 
state, in Stenophlebia and in Isophlebia. These characters are the sud- 
denly narrowed second cubital space in Platephemera, and the straight 
sector trigonuli inferior in Gerephemera, neither mentioned by the 
author. 
The three other fragments belong to the Neuroptera, and probably all 
to the Sialina. Oné of them is more related to the Corydalis type, the 
two others to the Chauliodes type. 
2. None of them have any relation to the Ephemeridæ, as is asserted 
by the author. 
3. None of the Devonian Insects are of a synthetic type. Besides 
that such a type could hardly be derived from the wing only of living 
Species, these specimens are too fragmentary for such conclusions. 
4. The previous stages of all were probably aquatio. 
5. No related species is known from the North American carbonifer- 
ous strata. Probably all insects known from them are terrestrial. Till 
a more complete account is given of Euephemerites, it cannot be consid- 
ered to be an insect wing. 
6. Concerning the four families proposed by the author, one, the 
Atocina, is out of the question, because belonging to the Odonata. The 
other three are based upon extremely vague characters, which are not 
justly to be considered family characters at all. 
The study of fossil insects, and especially the study of fragments of 
fossil insects, is doubtless extremely difficult. The most detailed knowl- 
edge of the living fauna is indispensable, and, as the specialist will in- 
evitably find, the actual literature is entirely insufficient for the details 
needed for comparison, and a very complete collection, such as does not 
yet exist here for any group, is necessary in order to avoid grave errors. 
