aa eee Te 
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' Beads. 
- 
THE FEATHERFOOT SPIDER, ULOBORUS PLUMIPES. nvr 
the centre; in the structure of the hub; in the preliminary spiral scaffold ; 
in the central concentrics, which correspond with the notched zone; in 
the form and distribution of the spirals; in the character of the 
AGen- ribbon decorations; in the manner in which the snare is swung 
ancien foundation lines in whatever site it may be placed; in the 
weaver. ? 
position of the spider underneath the web;—in all these points 
the spinningwork of Uloborus is analogous to that of Orbweavers, espe- 
cially Tetragnatha, or of the Orchard and Hunchback spiders. 
There is, however, one important difference. The spiral concentrics, in- 
stead of being composed of single lines covered with viscid beads, as in 
typical snares of the Orbitelariee, are composed for the most part 
of several very delicate filaments, although in certain parts the 
thread is single. To threads and filaments alike are often at- 
No Viscid 
_tached a number of minute objects, opaque, and for the most part amor- 
phous; but many of them being very small globes of a yellow color, per- 
Fic. 164. Circular ribboned decorations on the snare of Uloborus. 
haps the pollen of flowers. They adhere to the single threads, but more 
fully to the portions containing several distinct filaments. These opaque 
objects have so much the appearance of beads that a careless observer is 
likely to be deceived by them; at least, I was thus led astray in my first 
studies of the Uloborus snare. There are, however, no viscid beads upon 
any of the lines, although the thread is certainly very adhesive, chiefly 
I suppose by reason of the delicacy and flocculence of the fibre. The 
smooth point of a pencil touched to it does not adhere; but when my 
finger was laid upon a spiral it adhered as in the’case of a beaded web. 
In this respect the snare of Uloborus resembles that of the Triangle 
spider, Hyptiotes cavatus, and also certain species of the Clubion- 
Relations idee, such as Dictyna philoteichus and other species of that genus. 
oF Eee” This flocculent web was discovered and described by Blackwall, 
Spirals. 22d is produced by special organs known as the cribellum and 
calamistrum. The calamistrum is located upon the metatarsus 
of the hind pairs of legs. It resembles somewhat in form the flyers upon 
