1380 PROCEEDINGS OF SOCIETIES. 
face of the spinnaret, so that there is no communication 
between one and anether. The spmning glands may be di- 
vided into four varieties. The first consists of a large 
number of exceedingly minute cells, each containing a kind 
of nucleus, and furnished with a very fine duct. These are 
only found in the family of the Cinifloride, and are placed 
immediately beneath the imtegument, near the supplemen- 
tary spinnarets, with which they are connected. These 
glands evidently secrete the fine silk, which forms the floc- 
culus in the web of Ciniflo_(Clubiona) atrox and ferox. The 
next group of spinning glands is the most numerous and 
most constant of all the varieties. It consists of an immense 
collection of small oval, or fusiform, cells, with fine elastic 
ducts, which terminate principally in the anterior and pos- 
terior pairs of spinners. These probably secrete the fine 
threads, which weave the more delicate parts of the webs, 
and construct the cocoons in which the eggs are deposited. 
The third variety of silk glands contains several cartilaginous 
sacs, or convoluted tubes, of a firm or even hard consistence, 
but brittle and transparent. ‘These are often of a large size, 
especially in the different species of Epeira. They have fine 
inelastic ducts. Perhaps these secrete the adhesive lines 
which are placed on the geometric webs of spiders. The last 
and most interesting kind of glands are membranous sacs 
and tubes, some vermiform, others clavate, others furnished 
with branched cca. ‘They vary in size, some being very 
large. All have thickened and apparently fibrous walls, and 
they are all furnished with elastic ducts, having a fibrous ex- 
ternal coat, composed of distinct rings, which break up into 
separate pieces when the duct is stretched. From their con- 
struction, these sacs and ducts must possess a strong contrac- 
tile and expulsive power. They probably secrete the stronger 
threads, which are stretched between distant points, and 
form the framework of the webs; and they must also pro- 
duce the gossamer of the aeronautic spiders, for they are 
exceedingly large and numerous in Lycosa saccata and 
Thomisus cristatus—common aérial species—which require 
them for no other purpose, as they do not spin ordinary 
webs, being erratic in their habits. In most other species of 
Lycosa, also, the spinning organs are very slightly developed. 
The ducts from both the cartilaginous and membranous 
glands terminate in all the three ordinary pairs of spinnarets ; 
several from the latter may be traced into the long triar- 
ticulate spinnarets of Agelena labyrinthica. 
