192
THE SPIDERS OF EPPING FOREST.
The Araneae are oviparous creatures, without metamorphoses, feeding upon
insects or other small animals which they capture either with or without the
aid of a silken snare.
SUB-ORDER MESOTHELAE (Pocock).
Upper surface of abdomen with traces of segmentation in the form of
distinct transverse plates. This small sub-order, of which we have no British
representative, may be regarded as a transitional group, visibly approximating
the Pedipalps, and, therefore, as the probable ancestral stock from which the
various spider families have developed.
SUB-ORDER OPISTHOTHELAE (Pocock).
Abdomen apparently non-segmented. A small anal tubercle is often
present which may reasonably be regarded as a vestigial segment, but no
known representatives of this sub-order possess any structure which could be
mistaken for the dorsal plates of the Mesothelae.
SECTION I. MYGALOMORPHAE.
Spiders with four laminated tracheae and with the fangs articulated so as
to permit of motion iu a vertical plane.
The more ancient spiders included in this section exhibit striking affinities
with the Mesothelae. The Mygalomorphae are of large size and, as a rule,
not brilliantly coloured. One rather aberrant family is represented in this
country, namely, Atypidae.
SECTION II. ARANEOMORPHAE.
Spiders with two laminated tracheae (with rare exception) and with one
or occasionally two openings leading to tube-tracheae (absent in a few cases).
The fangs are articulated so as to permit of motion in a horizontal or oblique
plane.
Although apparently developed from a group identical with or closely
allied to the Mesothelae, the earlier forms of Arachnomorphae do not
approximate the ancestral type so closely in some respects as do the
Mygalomorphae.
We may conveniently divide the Araneomorphae into three
series, Dysderiformae, Drassiformae and Argiopiformae.
SERIES I. DYSDERIFORMAE.
Spiders of an early type with six nocturnal eyes and generally two tube-
tracheal openings situated close to the laminal tracheae. The tarsus of the
male palpus closely resembles that of the female, the joint being entire or
occasionally very slightly hollowed. The palpal bulb is of extremely simple
structure, usually more or less of a flask-like form and containing a spiral
sperm tube. Palpal apophyses are not present. The genital aperture of the
female is a simple transverse opening provided with neither epigynal plates
nor clavus. The tarsal claws are sometimes two and sometimes three in
number.