tliere is a thicket below, it suddenly faUs down. I may remark,
that I have distinctly seen the thread from the spinners,
lengthened by the will of the animal while yet stationary,
as preparatory to its fall. If the ground is clear
beneath, the Epeira seldom falls, but moves quickly through
a central passage, from one to the other side. When still
further disturbed, it practices a most curious manoeuvre:
standing in the middle, it violently jerks the web, which is
attached to elastic twigs, till at last the whole acquires such
a rapid vibratory movement, that even the outline ot the
spider’s body becomes indistinct.
I will here just mention a gregarious Epeira found in grea
numbers near St. Fe Bajada, the capital of one ol the
provinces of La Plata. The spiders were of a large size, and
of a black colour, with ruby marks on their backs. Ihey
were nearly all of one dimension, and therefore could not
have been a few old individuals with their families. Ihe
webs were placed vertically, as is invariably the case with
the genus Epeira: they were separated from each other by
a space of about two feet, but were aU attached to certain
common lines, which were of great length, and extended to
all parts of the community. In this manner the tops ot
some large bushes were encompassed by the united nets.
Azara* has described a gregarious spider in Paraguay, which
Walckenaer thinks must be a Theridion, but probably it is
an Epeira, and perhaps even the same species as mine. 1
cannot, however, recoUect seeing a central nest, as large as a
hat, in which, during autumn when the spiders die, Azara
says the eggs are deposited. These gregarious habits in so
typical a genus as Epeira, present a singular case among
insects, which are so bloodthirsty and solitary, that even the
sexes attack each other.
In a lofty valley of the Cordillera, near Mendoza, I found
another spider with a singularly-formed web. Strong lines
radiated in a vertical plane from a common centre, where
* A z a r a ’s V o y ag e , v o l. i., p . 2 13.
the insect had its station; but only two of the rays were
connected by a symmetrical mesh-work; so that the net,
instead of being, as is generally the case, circular, consisted
of a wedge-shaped segment. All the webs were similarly
constructed.
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