ON THE NETS OF GEOMETRIC SPIDERS. 281 
line approaches the several circumvolutions of the 
unadhesive spiral line, the spider bites them away, 
being sensible that they are no longer of any use to 
her ; and this fact explains why they are never seen 
intermixed with the circumvolutions of the former in 
finished nets. The viscid spiral line, whose circum- 
volutions are nearly equidistant, being separated by 
a space varying, according to the size and species 
of the animal, from about a thirtieth to six or seven 
tenths of an inch, is thus produced till it extends to 
the most proximate circumvolutions of the unadhesive 
spiral line, which, occupying the central part of the 
net, are suffered to remain; it is then discontinued, 
and the spider, making choice of some retired spot 
in the vicinity, there constructs a cell, or selects a 
situation in which she may conceal herself from ob- 
servation. From the centre of the net to this re- 
treat she spins a line of communication, composed 
of several threads united together throughout their 
entire length, the vibrations of which speedily inform 
her of the capture of her prey; and here her labours 
terminate. 
Such is the process, with some slight modifications 
now to be noticed, employed by the Geometric 
Spiders in the formation of their snares. One spe- 
cies, the Lpetra calophylla of M. Walckenaer, gene- 
rally converts a radius into a line of communication 
between the net and its retreat, instead of spinning 
a separate line for that purpose; and this peculiar 
