of the web.  When disturbed, it acts differently according to circumstances:  if there is a thicket below, it suddenly falls down; and I have distinctly seen the thread from the spinners lengthened by 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 side to the other.  When still further disturbed, it practises 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 of the spider’s body becomes indistinct.

[Illustration:  FOUR DIFFERENT SPIDERS.]

It is well known that most of the British spiders, when a large insect is caught in their webs, endeavor to cut the lines and liberate their prey, to save their nests from being entirely spoiled.  I once, however, saw in a hot-house in Shropshire a large female wasp caught in the irregular web of a quite small spider; and this spider, instead of cutting the web, most perseveringly continued to entangle the body, and especially the wings, of its prey.  The wasp at first aimed in vain repeated thrusts with its sting at its little antagonist.  Pitying the wasp, after allowing it to struggle for more than an hour, I killed it and put it back into the web.  The spider soon returned; and an hour afterwards I was much surprised to find it with its jaws buried in the orifice, through which the sting is protruded by the living wasp.  I drove the spider away two or three times, but for the next twenty-four hours I always found it again sucking at the same place.  The spider became much distended by the juices of its prey, which was many times larger than itself.

I may here just mention, that I found near St. Fe Bajada, many large black spiders, with ruby-colored marks on their backs, having gregarious habits.  The 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 all attached to certain common lines, which were of great length, and extended to all parts of the community.  In this manner the tops of 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 with mine.  I cannot, however, recollect seeing a central nest as large as a hat, in which, during autumn, when the spiders die, Azara says the eggs are deposited.  As all the spiders which I saw were of the same size, they must have been nearly of the same age.  This gregarious habit, in so typical a genus as Epeira, among insects, which are so bloodthirsty and solitary that even the two sexes attack each other, is a very singular fact.

[Illustration:  JUMPING SPIDER.]

WHAT I SAW IN AN ANT’S NEST