Structure and Economy of Spiders. 483 
effected, it will suffice to detail the. proceedings of a single spe- 
cies; and as Epeira calophylla is of frequent occurrence about 
retired buildings situated in the country, and, consequently, 
may be procured without difficulty, I shall select it for the pur- 
pose. Preparatory to casting its integuments, this spider spins 
several strong lines in the vicinity of its snare, from which it 
suspends itself by the feet and a filament proceeding from the 
spinners. After remaining for a short time in this situation, the 
corneous covering of the thorax gives way,—not in the medial 
line of the dorsal region, as Dr. Leach's statement would seem 
to imply, but laterally, disuniting immediately above the inser- 
tion of the mandibles and legs, so that the head and thorax are 
the first parts liberated. The line of separation pursues the 
same direction till it extends to the abdomen, which is next dis- 
engaged; the extrication of the legs being the last and greatest 
difficulty which the spider has to overcome. As the suspensory 
filament connected with the spinners of the exuviz is consider- 
ably shorter than the legs, and does not undergo any sensible 
alteration in length, the abdomen, during the process of moult- 
ing, becomes gradually deflected from its original horizontal 
direction, till it assumes a vertical position nearly at right 
angles with the thorax. By this change of posture, attended 
with numerous contortions of the body and alternate contractions 
and extensions of the limbs, the spider is ultimately enabled to 
accomplish its purpose. The spines with which the legs are 
provided no doubt contribute to facilitate the operation greatly ; 
for as they are directed down the limbs, and are moveable at 
the will of the animal, when it has partially withdrawn the legs 
from their sheaths by contracting them, it can prevent them 
from re-entering by slightly erecting.the spines and thus bring- 
ing their extremities in contact with the inner surface of the 
integuments. When the spider has completely disengaged itself 
from 
