186 THE ESSEX NATURALIST
In O. spinosus hatching is a quick process. The young do not
eat the egg membranes. The first moult occurs as the tiny
creature hatches or immediately after. The cast skin may there-
fore be found in or near the egg membranes. I have observed
eight moults in this species. Dr. Todd (unpublished) records
seven in three other species.
The young are difficult to rear. Mons. Gueutal's method of
hurrying them through their lives in a constant temperature oven
at 30° C. seems satisfactory for making observations on the
number of instars, moulting, etc.
The table on pages 188 and 189 gives details of the life-cycle of
each species so far as it is known. Further observations are
required to establish when some species hatch from the egg, when
the young mature and when the adults lay eggs.
From this table it will be seen that the greatest number of
adults live towards the close of summer; and that three types of
life-cycle can be recognised, namely (i) those species which pass
the winter in the egg stage and which mature towards the end of
summer, (ii) those in which both young and adults can be found
more or less at any time—these are the ground living species living
in a relatively sheltered situation and (iii) those which mature in
the early summer and lay eggs from which the young hatch and
spend the winter in the immature stage, e.g., Platybunus triangu-
laris.
ECOLOGY
Omitting the detailed analysis of the various habitats and
frequency of occurrence of each species which I hope to publish
in due course, we can consider the ecology of the British harvest-
spiders from two aspects:
VERTICAL DISTRIBUTION
Group (a) : species which usually live on the ground under
stones, under logs, in moss, in plant debris, especially in woods.
These species have short, or shortish legs and rather small eyes.
They live in this habitat all their lives.—Homalenotus quadriden-
tatus (Cuv.), Oligolophus meadii Camb., Opilio saxatilis, Trogulus
tricarinatus, Anelasmocephalus cambridgei (Westw.) (Plate 13 (d));
Nemastoma chrysomelas (Herm.) and N. lugubre (Muller) (Plate
13(a)).
Group (b): species which live mainly amongst low vegetation
(the field layer) of grass and other herbaceous plants, but whose
young stages (especially the very early instars) occur with group
(a): Nelima silvatica (Simon), Leiobunum blackwallii Meade,
L. rotundum (Latr.), Mitopus morio (Fab.), Oligolophus tridens
(C. L. Koch), Lacinius ephippiatus (C. L. Koch), Platybunus
triangularis, Megabunus diadema, Phalangium opilio.