MOULTING HABITS OF SPIDERS, 95 
Orbweayers moult as follows:! Preparatory to casting its skin the 
spider spins several strong lines in the vicinity of its snare, from which 
it suspends itself by the feet and a thread held in the spinners. After 
remaining for a short time in this situation the covering of the ceph- 
alothorax gives way laterally, disuniting immediately above the insertion 
of the falees and legs, so that the head and thorax are the first parts 
liberated. 
The line of separation pursues the same direction, passing midway 
through the pedicle until it extends to the abdomen, which is next disen- 
gaged. As the thread held by the spinnerets is usually shorter 
Orbweav-than the legs and undergoes little alteration in length, the ab- 
conte domen is gradually deflected from its horizontal to a vertical 
’ position, nearly at right angles with the cephalothorax. By this 
change, attended with numerous contortions or undulatory movements of 
the body, the spider frees the abdomen, which falls back in a wrinkled 
saclike mass united to the dorsum of the cephalothorax by the upper half 
of the tegument of the pedicle, 
The legs are the last and most difficult to detach, but are drawn out 
downward and usually entire by successive muscular contractions and 
strains, with brief intervals of rest. Blackwall thinks that the spines with 
which the legs are provided facilitate the operation; for, as they are di- 
rected down the limbs and are moyable at the will of the animal, when 
it has partially withdrawn the legs from their sheaths by contracting 
them, it can prevent them from reéntering by slightly erecting the spines 
and thus bringing their extremities in contact with the inner surface of 
the integument. As the spines also and simultaneously with the legs 
undergo moulting, it may be doubted if their service in this respect is 
very great. 
When the spider has completely disengaged itself from the sheath it 
remains for a short period relaxed and exhausted, suspended solely by a 
thread from the spinnerets. The entire process, as above de- 
After . : : 
Moult,  ‘Sctibed, may be completed in about twenty minutes under normal 
conditions, but varies in length of time according to cireumstan- 
ces. After a short rest the spider adjusts its position, making itself more 
secure upon the suspensory lines by seizing them with the feet; stretches 
its legs, bends and unbends them, passes them through the mouth, and 
hangs in repose until its strength is sufficiently restored and its limbs have 
acquired the requisite firmness, when it ascends its filaments and seeks 
its nest or retreat, or takes position upon its snare.? 
1 This detailed description is that of an Epeiroid, and is made from my own obserya- 
tions combined with those of Blackwall, Wagner, and others. 
* Blackwall, Researches in Zoology, pages 306, 307; British Spiders, Introduction, page 7 ; 
Id., Ann. and Mag. Nat. Hist., XV., 1845, page 230; Id, Trans. Linn. Soc., XVI., pages 
482-484; Wagner, La Mue des Araignées, page 284. 
