2 NUMBER OF SPECIES. 
thousand species are known. Even this large number 
is certainly far short of those actually in existence.’ 
I have kept in captivity about half of our British 
species of ants, as well as a considerable number of 
foreign forms, and for the last few years have generally 
had from thirty to forty communities under observation. 
After trying various plans, I found the most con- 
venient method was to keep them in nests consisting 
of two plates of common window glass, about ten 
inches square, and at a distance apart of from +1; to 
1 of an inch (in fact just sufficiently deep to allow 
the ants freedom of motion), with slips of wood round 
the edges, the intermediate space being filled up with 
fine earth. If the interval between the glass plates 
was too great, the ants were partly hidden by the 
earth, but when the distance between the plates of 
glass was properly regulated with reference to the 
size of the ants, they were open to close obser- 
vation, and had no opportunity of concealing them- 
selves. Ants, however, very much dislike light in 
their nests, probably because it makes them think 
themselves insecure, and I always therefore kept 
the nests covered over, except when under actual 
1 T have had some doubt whether I should append descriptions 
of the British species. On the whole, however, I have not thought 
it necessary todo so. They are well given in various entomologica] 
works: for instance, in Smith’s Catalogue of British Fossorial 
Hymenoptera; Saunders’ Synopsis of British Heterogyna; and in 
Mayr’s Die Hwropdischen Formiciden, all of which are cheap and 
easily procurable. I have, however, given figures of the principal 
species wilh which I have worked. 
