XIV SHEET-WEBS 353 
The snares of these spiders are exceedingly closely woven of 
very fine silk, and take a long time to complete. The process of 
their construction may be watched by keeping an <Agelena 
labyrinthica confined in a box with a glass front, and the web, 
kept free from dust, is a beautiful object, as its fine texture 
eradually becomes visible as a delicate transparent film which 
develops by imperceptible stages into an opaque white sheet. 
The excessive fineness of the silk makes it difficult at first to see 
what is taking place. The animal is seen to be busily moving 
about, but the result of its labours only gradually becomes visible. 
A few delicate foundation-lines are first stretched across the 
compartment in which it is confined, and upon these the spider 
walks to and fro incessantly with a serpentine motion, and by 
and by a muslin-like floor of silk comes into view. 
An examination of the spinnerets throws some light upon 
the operation. The posterior pair are very long and mobile, and 
the hair-like spinning-tubes are distributed on their under 
surface. The cephalothorax and abdomen are far more rigidly 
connected in Agelena than in the Orb-weavers, but its length of 
leg and the length and mobility of its posterior spinnerets 
enable it to give a wide lateral sweep as it walks along, strewing 
fine silken threads upon the foundation-lines already laid down. 
Some hours elapse before even a moderately stout web is con- 
structed, and for long afterwards the spider devotes odd 
moments of leisure in going over the ground again and strewing 
new silk upon the gradually thickening web. At one corner a 
silken tube of similar structure is formed, and in this the spider 
awaits the advent of any insect which may alight upon the sheet, 
when it immediately rushes forth and seizes it. 
The webs of the Dictynidae are very similar in general 
appearance to those of the Agelenidae, consisting of a closely- 
woven sheet with a tubular nest. They are to be found, more- 
over, in similar situations, stretching across the angles of walls 
in cellars or outhouses, though some species prefer an outdoor 
existence. Crannies in rock form convenient sites for such 
snares, but the family is not without its representatives in still 
more open situations. The web, though so similar to that of 
Agelena, is, however, constructed in a different manner. In the 
Dictynidae neither the legs nor the spinnerets are unusually long, 
and they do not strew the foundation-lines by a swinging motion 
VOL. IV 2 A 
