482 Mr. Blackwall on the 



tact they present. At a 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 My gale 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 tibiae, 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 (J rawea domesticavn 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 Encyclopcedia 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 elucidate 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, 



