482 Mr. BLACKWALL on the 
tact they present. Ata very low estimate, there are on the 
slender bristles which form the brushes occurring on the inferior 
part of the tarsi, and the terminal joint of the pediform palpi 
of adult females of the species Mygale avicularia, more than 
6,000,000 hairs of extreme delicacy, a large proportion of which 
can be applied by the spider to bodies with plain surfaces. If 
the finger be drawn gently along the underside of the tarsi, from 
their extremities towards the tibize, they will be found to adhere 
powerfully to the cuticle ; the sensation occasioned by this pro- 
ceeding exciting in the mind the idea that they are smeared 
with some viscous matter. There can be no doubt, therefore, 
that the influence they exercise is in the direction indicated 
by this observation. A setaceous bristle from one of the tarsi 
of Mygale avicularia, very highly magnified, is represented by 
Fig. 5; and care must be taken not to confound these tarsal 
appendages with the compound hairs which clothe the limbs of 
some spiders (Aranea domestica in particular), one of which is 
represented by Fig. 6, on a large scale. 
Dr. Leach, in treating upon spiders in the article Annulosa, 
published in the Supplement to the Encyclopedia Britannica, 
p. 435, remarks that ** when about to cast their covering, they 
suspend themselves in some corner, and creep out of a crack 
which takes place on their back, gradually withdrawing their 
legs from the skin, as if from a glove.” With deference to so 
accomplished a zoologist, I may be allowed to observe that this 
statement is not in strict accordance with my own experience ; 
and as I do not remember to have met with a satisfactory account 
of the moulting of spiders in the course of my reading, I shall 
endeavour to diücidnte this curious subject, by giving such par- 
ticulars relative to it as have fallen under my notice. 
Considering. the apparent uniformity of the process by which 
this important change in the external condition of spiders is 
effected, 
