518 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
used colei, would kill them, except after so long an exposure that the 
natural histological condition was quite destroyed. The first fluid tried 
was a saturated watery solution of corrosive sublimate. In this reagent 
the lame lived and moved about for 20 hours. At the end of that time 
they seemed to be dead, and they were then washed and put into 70 per 
cent, alcohol, where they soon revived, and exhibited lively movements 
for one hour longer. A table is given of a number of fluids in which 
these larvae lived from four and a half hours to ten seconds. In all 
cases the larvae were entirely submerged, with the exception of the end 
of the tail, which the animal held at the surface of the fluid. It is 
through the tail that these larvae breathe, aud therefore they are able 
to obtain air freely, while their bodies are exposed to the action of the 
killing fluid. This gives us a much better test of the penetrating power 
of reagents than we could have in the case of larvae which are entirely 
submerged in the fluid. The larvae could be quickly killed by the 
standard fluids if a slit were previously cut in the integument. 
American Fossil Cockroaches.* — Dr. II. Scudder reports that more 
than 300 American specimens of Palaeozoic cockroaches have passed 
under his eye. These belong to at least 132 species, belonging them- 
selves to 14 genera. The recent extension of our knowledge of these 
ancient insects is largely due to investigations in two new localities, 
respectively near to Cassville and Richmond. In a period in which the 
total number of species has more than trebled, the increase of European 
species has been about 50 per cent., while the American have multiplied 
nearly eightfold. With regard to the relative size of the ancient cock- 
roaches, no one, the author remarks, can handle many specimens without 
being struck with the fact that they are of large size. In each genus 
the average size decreases with the lapse of time. 
Amongst the various subjects with which he deals in the introduc- 
tory remarks, attention is drawn to a topic which, as he justly remarks, 
is unusual in such a connection. It is the possibility of mimicry in 
Palaeozoic cockroaches. It seems to Mr. Scudder to be fairly reason- 
able to look upon some forms of carboniferous cockroaches as probably 
imitative, and thereby protective. The first fossil cockroach wing ever 
described was first described as a fern-leaf, and in all or nearly all the 
localities where their remains have been found they are associated with 
fern-leaves in immense abundance. In one point only can a cockroach 
wing be distinguished at once, but it is a feeble point, and one that 
would often be noticed only by an expert. The memoir is made the more 
complete by a list of the described European Palaeozoic cockroaches. 
Myriopoda. 
Classification of Diplopoda/f — Mr. O. F. Cook remarks that the 
structure and distribution of the Diplopoda make it advantageous, and 
usually easy, to arrange them into species ; an apparent, and probably 
sufficient cause for this is the close similarity of the life-histories, habits, 
and food of all Diplopoda. All are scavengers, and there has been scarcely 
any response to calls for special adaptations. The species are not only 
* Bull. U.S. Geol. Survey, No. 124, 1895 (17G pp. and 12 pis.). 
t Amer. Natural., xxx. (1896) pp. 681-4. 
