WEB-SPIDERS. 
22 3 
instance, the spinning instincts were directed solely to the protection of the species 
during infancy, growth, and maturity; and we may conclude that, apart from the 
cocoon, the initial stage in the development of web-making was the formation of 
some kind of tubular retreat. From this point the evolution of the spinning 
industry — perhaps the most important and interesting feature in the natural 
history of spiders—seems to have progressed 
along two lines. Along one the tubular retreat 
becomes gradually elaborated until it culmin¬ 
ates in the trap - door nest; while along the 
other the tube is to a greater or less extent, or 
even wholly, superseded by a new structure, 
the snare; the latter attaining its greatest 
perfection in the triangular snap - net of 
Hyptiotes, or the beautiful and symmetrical 
orb-web of the common garden spider. At 
the outset it is possible that the simplest form 
of snare arose from the spinning of supporting 
lines around the mouth of the tubular retreat, 
and if these served to entangle prey it is clear 
that a new and easy method of obtaining food 
would be opened up, and the habit of spinning 
webs of this nature would be fostered until 
the various kinds of nets became evolved. 
Another use to which the spinning of threads 
may be put is that of flying. This is especially 
practised by young spiders, who on fine 
autumnal days climb to the tops of bushes 
and fences, and, raising the abdomen into the 
air, emit a thread or tuft of threads which 
blowing away in the wind soon become large 
and strong enough to carry the spider, sometimes to great heights above the ground. 
It was originally supposed that these threads were spun by a species called the 
gossamer-spider, but it is now known that the habit is practised by young spiders 
of different families. Floating about in the air, these fine threads meet and, 
becoming entangled, form masses of web, which ultimately fall upon the bushes 
and fields, sometimes covering them thickly with a white coating of fine silk. 
Segmented Group, —Suborder Mesothelse. 
Spiders may be divided into the two main groups, Mesothelce and Opisthothelce . 
In the former, the spinning mammillae, eight in number, are situated in a cluster in 
the middle of the lower surface of the abdomen; the upper surface of the latter 
being covered with a series of nine dorsal plates, resembling those of scorpions, 
while its lower surface is similarly furnished with two sternal plates covering the 
first and second pairs of lung-sacs. In these characters the group differs from other 
spiders, and in having the abdomen segmented it constitutes a kind of link 
