NOTES ON MYRMECOPHILOUS SPIDERS. 421 
progenitive instincts are of such transcendent importance that 
all the other instincts of the species, including, of course, those 
of alimentation and nest-building, become merely tributary or 
ancillary. In ants, especially, the instincts relating to the 
nurture of the young bear the aspect of a dominating obsession. 
The very strength and scope of. such instincts, however, render 
the insects more susceptible to the inroads of hosts of guests, 
commensals and parasites.” 
I now propose to try and classify our ants’ nests’ spiders 
into these three groups. 
Grovp I. 
Tha yreosthenius biovatus, Cambr.—This little spider is found 
in the hillocks of Formica rufa, and anyone who cares to spread 
a few handfuls of the nest materials on to a sheet or paper will 
be sure to find it. In April, 1900, 1 took an adult female in a 
nest of F’. rufa in Guestling Wood, near Hastings. This was its 
first British record! Messrs. Butterfield and Bennett tell us that 
it is not uncommon in nests of this ant in the Hastings district, 
but that the adult males are rarely found. I have found it with 
its hosts at Weybridge, Oxshott, Woking, Pyrford, Enfield, Blean 
Woods, Knowle, and Nethy Bridge. I have taken both sexes, 
and I may.say I have found it in rufa nests in every month in 
the year. Jackson has found it in nests in the Tyne Valley, and 
Bagnall at Corbridge, Winlaton, and Chopwell. I believe it is 
to be found wherever F’. rufa occurs. Father Wasmann records 
that F’. rufa and F’. pratensis are its normal hosts. Mr. Bagnall 
took a male and female in the Derwent Valley away from ants, 
but if is only natural to suppose that it sometimes leaves the 
nests and strays about in search of fresh. ones. 
On its habits I have the following notes:—On April 26th, 
1901, I brought up from Oxshott six specimens of this spider 
from a nest of F. rufa, and introduced them into my “observa- 
tion nest” of the same ant. They at once entered the galleries, 
the ants paying no attention to them. I did not see any of 
them again till June 23rd, when a female came up, accompanied 
by a number of young ones, so they must have bred in my nest. 
After this specimens were observed on June 25th, 27th, 30th ; 
July 18th, 21st, and 27th. On Sept. 19th quite a number were 
walking about in my nest. The last specimen observed was on 
