414 ZOGEOGY 
and posterior. The rays are each continued into nerves; of 
these the first pair is continuous with the circum-oesophageal 
commissures, the second supplies the pedipalpi; the next four 
stout rays supply the four legs, and the posterior pair is con- 
tinued back into the abdomen, the two nerves lying so close 
together as to be often mistaken for one. 
The sense organs of spiders are limited to eyes which are 
always simple, and to taste organs. The number and arrange- 
ment of the eyes are of great use in classification, the various 
families having a different and definite arrangement of these 
organs. In Epeira the visual organs are situated on the 
anterior part of the cephalothorax; there are four large eyes 
arranged quadrilaterally, and on each side of the square are two 
smaller eyes, the members of each pair being connected by a 
ridge of chitin. 
The male, as is usually the case in spiders, is smaller than 
the female, and whilst the latter usually sits in the centre of 
the circular web, the male is to be found hidden under the leaves 
of a neighbouring bush. . 
The ovary is situated in the abdomen; it lies ventrally, 
and is surrounded by the caeca of the liver and spinning-glands. 
It consists of two hollow tubes which unite posteriorly, and 
are continued backward as a thread; anteriorly each ovary is 
continuous with an oviduct; during the breeding season the 
ovaries are much swollen, and the ova form projections on the 
walls of the organ (Fig. 236). The oviducts open into a uterus, 
and this opens into a recess on the ventral wall of the 
abdomen. ‘The external genital armature of the female is 
called the epigynium; it is often of a very complex character, 
and its nature is of considerable use in determining the species 
of a spider. In addition to the opening of the oviducts, it 
also receives the external ducts of the two spermathecae ; these 
ducts may be short and wide, or long and coiled. There are 
also a pair of internal ducts which lead from the spermathecae 
to the oviduct, and along which the spermatozoa pass to 
fertilise the ova before they are laid. The epigynium is 
rendered more complex by the presence of numerous structures 
which serve to guide the palpal organs of the male into the 
external openings of the spermathecae; it only exists in its 
