ON ARACHNIDA. 
485 
of autumn, and a large species of scolopendra, are enemies 
from which few of them escape. This scolopendra attacks the 
largest tarantulae, and, after an obstinate combat, succeeds in 
killing them, and taking possession of their habitation. The 
two sexes live separately, and, except during the season of 
reproduction, carry on a mortal warfare. This tarantula is 
susceptible of anger to an extreme degree, especially when 
forced to quit its habitation, which it never does without a 
desperate struggle. 
In the genus Salticus, the species named Aranea scenica 
by Linnaeus is very common, and remains generally on walls 
exposed to the sun, or on the glasses of casements, where it 
parades at all hours during the summer. It walks, as it were, 
by jerks, stopping short altogether after having gone some 
paces. It rises on its first feet, elevates the anterior part of 
its body, tefconsider on which side it shall leap; and it is 
thus that it seizes small insects, especially gnats, which it 
appears to prefer. When it has discovered the object of its 
prey, it approaches it softly, with gentle steps, until it comes 
to a distance which it can cross by a single jump, and fall 
upon the little animal which it has been watching. It does 
not fear to leap perpendicularly from a wall, because it always 
finds itself attached by a thread of silk, which it continually 
unwinds in walking, and which, under these circumstances, 
holds it suspended. The other species of Saltici also use the 
same precaution when they fall, either of their own accord or 
from some sudden impulse ; and this thread serves the pur- 
pose, being moved by the wind, to transport them with facility 
from one place to another. They can also re-ascend to the 
point from whence they had descended. 
Some individuals of the species above mentioned, and which 
Degeer kept in a box, spun against the walls little nests in the 
form of oval or rounded sacs, composed of white silk, and 
pierced on both sides with an aperture. Lister says that this 
