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Structure and Economy of Spiders. 415 
it can seldom be seen to advantage, unless artificial light be 
employed, some skill in the management of which is required 
in order to avoid disturbing the spider. "The modus operandi, 
as nearly as I can ascertain it by the most diligent observation, 
appears to be this. ‘The points of the lower row of spines are 
protruded between those of the upper row, and in passing across 
the extremities of the mammulz comb out the tortuous lines, 
which run into numerous flexures in consequence of not being 
kept fully extended. The purpose subserved by the upper row 
of spines seems to be the extrication of the tortuous lines from 
the spines of the lower row, by a slight motion outwards, which 
disehgages their points. Now, were the blue bands glutinous, 
this mode of proceeding would be quite unavailing ; it is only 
on the supposition, therefore, that they have a fibrous structure, 
that their adhesive property can be satisfactorily explained. 
When a sufficient quantity of the inflected filaments is produced, 
the spider again applies its spinners to one of the glossy lines, 
and attaches the flocculus to it. In this manner it proceeds 
with its labours, occasionally employing the combing apparatus 
of both hind-legs, till the web is completed. Should any of the 
flocculi be destroyed, or rendered almost useless by having their 
adhesive property impaired, new ones are constantly added to 
the snare. 
A more exact idea of the mechanism of the combing appara- 
tus than can be conveyed in words, will be obtained by inspect- 
ing the accompanying plate (Tas. XXXI.). 
Naturalists appear to concur in the opinion, that the tarsi of 
| spiders are armed at their extremities with three claws, which 
occupy the upper and anterior portion of the foot. ‘That this is 
the case with some species cannot be denied ; other species, how- 
ever, belonging to various genera, Mygale avicularia, Drassus me- 
3 lanogaster, 
