418 REVIEWS. 
the United States and British North America. There are three 
fossil species determinable, the oldest being from the Oolite forma- — 
tion at Solenhofen. The author gives a list of species of fossil in- = 
sects which have been at various times and by different observers — 
referred to this family. They are from formations older than the A 
Tertiary, mostly the Carboniferous. Among them are the strange 4 
forms described as Dictyoneura, Eugereon, Miamia, Hemeristia, 
Haphlophlebium, Platephemera, Homothetus, Xenoneura, Gerephe- — 
mera and Lithentomum. He says that “ Platephemera and Homo | 
thetus may possibly be of the Ephemerids, but there is nothing in : 
the figures to make this certain, and there is no reason for consid- 
ering that Xenoneura belongs to this family.” He then ré- 
marks :— ' : 
‘ Palæontologists have adopted a ridiculous course with regard 
e insect fossils. Whenever an obscure fragment of a well- 
often n 
the rite 
An insect allied to phemeridæ which chirped like a Locust 
(such as Xenoneura is imagined to have been) is a tolerable 
sample of these synthetic types. When a fossil comprises ont 
ent, or even a complete wing of an Ephemerid, it is 
possible to determine the genus, and impossible to assert the 
species. The utmost that can be learned from such a specimen 18 — 
the approximate relations of the insect. Neuration by itself ip 
not sufficient to define the species or even the genera of o 
Ephemeridæ. . 
This criticism on the labors of 
considering the great difficulties of the su 
with, scarcely fair, though perhaps in part deserved. 
palæozoic fishes; and others among the radiates and molluscs, our 
critic would not probably deny. And among the palæozoic insects, 
genera such as Eugereon, Dictyoneura, and Palephemera, are not 
considered as generalized types simply as a device of the puzzled 
and distracted entomologist for a means of escape from coming to 
any decision. These “random conjectures” are, if such, due to the 
