THE SPIDER 141 
moreover of two distinct parts, the head and thorax being 
fused together. The head-thorax bears eight legs, each 
of which consists of seven 
joints’ and ‘ends in a claw. 
The large number of joints 
enable —the legs to be 
easily moved about, an 
arrangement which greatly 
assists theyanimal in spin- 
ning its web. The eyes 
of the spider are not ¢ 
pound, but single — the 
number and plan of ar-— 
rangement of: these vary 
considerably » host spiders 
Fig. 94.—The Spider. have either six or eight 
eyes. 
In front of the head are the two feelers, which are 
really a pair of strong mandibles each ending ina powerful 
claw. These claws consist of two joints, the lower one 
being large and thick and having a 
furrow along its inner margin. Into 
this groove the outer claw-like joint 
can be folded when not in use—Just 
as the blade of a pocket-knife is shut 
back into the hollow space in the 
handle. The feeler is in reality a 
hollow tube leading to a poison gland. 
When the spider seizes its victim, it Fig. 95.—Mandibles, 
a showing one claw ex- 
can force a drop of poison through tended “and the other 
: . folded back int 
the claw into the wound with fatal x oor : 
results to the captured insect. 
Ov a: 
Seve! a; 
Respiration. On the under-side «i the abdomen near 
its junction with the head-thorax are two slits which open 
