OUR HOUSE SPIDERS. 
163 
part of tlie snare. The following description will serve to 
convey some idea of the manner in which the flocculi are fabri- 
cated, and of the curious apparatus employed in the process. 
There are on the metatarsi of the posterior legs of Ciniflo 
atrox two parallel rows of spines, moveable at the will of the 
animal, which are situated upon a ridge on the abdominal side 
of the superior surface of the joint, commencing a little below 
its articulation with the tibia, and terminating at a strong spur 
near its extremity. The spines composing the upper row have 
a considerable degree of curvature, and taper gradually to a 
fine point ; those of the lower row being stronger, more closely 
set, and less curved. This remarkable appendage, which has 
received the name of calamistrum, constitutes a striking cha- 
racter of the spiders included in the family of the Ciniflonidce. 
When the spider purposes to form a flocculus, it presses its 
spinners (which in the case of the Ciniflonidce are eight in 
number, the inferior pair supplying the material of which the 
delicate bands connected with the flocculi are fabricated) 
against one of the glossy lines constituting the foundation of 
its snare, and emitting from them a small quantity of the secre- 
tion of which its silken filaments are composed, attaches to it 
several fine threads, drawn out by advancing the abdomen a 
little, and kept distinct by a lateral motion of the spinners. 
The posterior legs are then raised above the plane of position, 
and the foot of one of them is applied to the superior surface 
of the metatarsal joint of the other, a little above its articula- 
tion with the tarsus, and the calamistrum is brought imme- 
diately beneath the spinners, at right angles with the line of 
the abdomen. By a slight extension of the joints of the pos- 
terior legs, the calamistrum is directed backwards across the 
spinners, the diverging extremities of which it touches in its 
transit, and is restored to its former position by a correspond- 
ing contraction of the joints. In proportion to the continua- 
tion of this process, in which the calamistra are employed 
alternately, the inflected lines and bands of the flocculus are 
found to be produced, the spider making room for them as 
they accumulate by elevating and at the same time advancing 
the abdomen, which it effects by slightly extending the joints 
of the third pair of legs, and contracting those of the first and 
second pairs. The flocculi thus elaborated are attached to the 
first spun glossy lines by the agency of the spinners, and in 
this manner the spider proceeds with its labours till the snare 
is completed. As this operation is generally performed in the 
night, it can seldom be seen to advantage, unless artificial light 
be employed, some skill in the management of which is re- 
quired in order to avoid disturbing the spider. The modus 
operandi appears to be this : — the points of the lower row of 
