THE SPIDERS OF EPPING FOREST. 193
These spiders as a rule spin no snare, but usually fabricate silken tubes
in crevices or beneath loose bark.
Three families are represented in Britain — Dysderidae,
Oonopidae, Scytodidae.
SERIES II. DRASSIFORMAE.
Spiders with usually eight eyes and with the tube tracheae opening in a
small transverse slit either just in front of the spinners or more rarely in the
centre of the abdomen. In one family Argyronetidae, two tube-tracheal open-
ings are present, placed very much as in the Dysderiformae. The eyes are
sometimes heterogeneous and sometimes homogeneous being then of the
diurnal type. The tarsus of the male palpus is more or less enlarged and
hollowed to receive the palpal organs. In the case of many of the more
primitive types the alveolus is small and the joint only slightly enlarged,
whereas in most of the highly specialised families the joint is greatly
expanded and the alveolus often occupies the greater part of its lower surface.
In many cases where these organs are of great complexity it is rather difficult
to recognise the exact condition of the joint, but careful examination in
different positions, aided occasionally by the use of the dissecting needle will
convince one that the form of the tarsus itself, however modified it may be,
has been produced by the hollowing out of the under surface of the more or
less enlarged joint. It will be noticed as a consequence that the alveolus
points directly downwards. The tibial joint cf the male palpus is usually
furnished with one or more apophyses. These are usually in the form of
strong, chitinous projections, and are very often of a darker colour than the
general surface of the joint. When only one apophysis is found it generally
springs from the anterior external angle of the joint and when several are
present the most highly developed one will usually occupy this position
Patellary and femoral apophyses are occasionally present. The genital
aperture of the female is provided with more or less developed epigynal plates
but is without a clavus. The tarsal claws are sometimes two and sometimes
three in number.
These spiders as a rule spin no true snares, but a few species surround
the extremity of their tubular retreats with a more or less extensive sheet of
web and lie in wait for insects which may be unfortunate enough to alight
upon this structure. A well known example of this form of web is found in
the "cobweb" with which the corners of our rooms are adorned (?)
Fifteen families of Drassiformae are represented in this
country, namely Drassidae, Clubionidae, Anyphaenidae, Spar-
assidae, Philodromidae, Thomisidae, Salticidae, Agelenidae,
Hahnidae, Argyronetidae, Dictynidae, Eresidae, Pisauridae,
Lycosidae, Oxyopidae.
SERIES III. ARGIOPIFORMAE.
Eight-eyed spiders with one pair of laminal tracheae and an indistinct
opening leading to tube-tracheae placed not far from the spinners. In one or
two instances tube tracheae are apparently absent. The tarsal claws are