218 
Psyche 
[September 
dytiscid condition. The so-called mesosternum should cer- 
tainly be re-examined with this possibility in view. 
To restate the case, Palaeogyrinus is a fossil which looks 
like a dytiscid, with a coxal structure demanding that the 
posterior and no other legs be highly developed, and which 
is said in the original text to be poorly preserved in the 
very place where the reconstruction is most remarkable. 
The conclusion must be that the insect was a dytiscid, but 
that it may have had an unusually large mesosternum. It 
is rather surprising that these facts have not been brought 
out before. 
I do not believe it is possible to place Palaeogyrinus ac- 
curately with relation to living genera, and see no reason 
to attempt it, since the placing would be a matter of guess 
work and might lead to confusion. The genus is interesting, 
therefore, chiefly because it is an example of a more or less 
typical dytiscid from the Upper Oligocene. It has also a 
temporary interest in that it provides an excuse for a few 
remarks on the place of fossils in the study of Coleoptera. 
Among orders where there are good characters in the 
wing venation fossils are often reliable, as they are in 
other groups when good series of good specimens are avail- 
able, as, for instance, in the case of the Florissant ants 
which have recently been studied by my friend Dr. F. M. 
Carpenter. Unfortunately, however, the parts of beetles 
which are usually preserved have few diagnostic characters, 
nor are good series of fossil specimens usually obtained. The 
placing of a species by examination of a single elytron 
from any but the most recent deposites must depend upon 
the unwarranted assumption that the beetle fauna of a 
given period was practically the same as that now existing. 
It is difficult to see the value of generic and specific descrip- 
tions of such nearly unidentifiable remains, when the great- 
est care and some faith are required to classify even a 
fairly complete specimen. This does not mean that fossil 
beetles have no value, but rather that their value is limited, 
the limit depending in each case on the number of char- 
acters actually observable in the fossil itself. There is a 
good deal of random guessing and specious reasoning to be 
