366 ARACHNIDA—ARANEAE CHAP. 
constructs a cocoon containing, on an average, 1150 eggs. As 
many as 2200 have been counted in exceptional cases. Even 
this number is exceeded in the case of some of the great 
Aviculariidae. Theraphosa leblondi deposits as many as 3000 
egos. The large European Epeirids, 2. guadrata and EL. diademata, 
lay about 600 eggs, those of Lycosa narbonensis reaching about 
the same number. Those American spiders which have been 
described as stringing up a series of cocoons in their webs usually 
attain about the same aggregate, the eggs being less numerous 
in each cocoon. 
These are examples of fairly large and fertile spiders. In the 
case of other species the number of eggs laid is exceedingly small. 
Ero furcata makes a single cocoon containing six eggs. Synageles 
picata, an ant-like Attid, lays only three. Oonops pulcher con- 
structs several cocoons, but each contains only two eggs. The 
egos of Cave-spiders, and such as live in dark and damp places, 
are generally few in number. Anthrobia mammouthia, for 
example, an inhabitant of the great American caves, deposits only 
from two to five eggs. 
Our knowledge of the special perils which beset particular 
species 18s so incomplete that we are often at a loss for the 
reason of this great inequality in fertility. For instance, how 
does Synageles picata maintain its numerical strength by laying 
only three eggs, when, as M‘Cook points out, its resemblance to 
the ant, though advantageous to the adult spider, affords no pro- 
tection to the egg? Our knowledge must be greatly extended 
before we are able to account for particular cases. Many 
influences hostile to spiders as a group are, however, well known, 
and we may here enumerate them. 
Natural Enemies.—The precautions taken by the mother in 
constructing the cocoon render the inclemency of the weather 
very much less destructive to the eggs than to the newly-hatched 
young. Nevertheless, among spiders inhabiting swampy regions 
great havoc is wrought by the occasional wholesale swamping of 
the cocoons by floods. Professor Wilder considers the great 
fertility of Mephila plumipes necessary to counterbalance the 
immense destruction worked by the heavy rains upon their 
cocoons, which are washed in great numbers from the trees, to 
the leaves of which they are attached. But such exposed situa- 
tions are avoided by many species, and their eggs, enclosed in 
