178 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 
an old fashioned spinning wheel, and is apparently used to separate into 
a flossy mass the threads of silk as they issue from the spinning glands, 
Bertkau, in an article on the cribellum and calamistrum, has shown cer- 
tain secreting glands at the ends of the fine tubes which have their 
outlets in the former organ. It is not improbable, in view of this dis- 
covery, that the viscidity of the flocculent spirals 
of Uloborus and other spiders possessing this 
organ is caused in some measure by a slight 
secretion from these glands. 
It is the possession of cribellum ‘and cala- 
mistrum by Uloborus and Hyptiotes which has 
led yarious arachnologists to separate 
these two genera from the Orbweavyers. 
Emerton, for example, following Black- 
wall, Keyserling, and Bertkau, assigns 
Sic tas ceecaes oe ee them to the Clubionide. Without entering at 
showing the cribellum, cb. P, pos- length into the reasons, based upon structure, for 
en ne icntema ane: dissenting from this opinion, I have felt con- 
nerets; ca, calamistrum. (After Ss i on, ve 
Blesewelly strained, on the grounds of their spinningwork 
alone, to place both these genera among the Orbitelarise, where indeed such 
a distinguished systematic arachnologist as Professor Thorell has already 
placed them, and continues to keep them, notwithstanding all the objec- 
tions that have been advanced by the able naturalists who have espoused 
the other view. 
Mr. Emerton has made some studies of the web of Uloborus Walck- 
enaerius, the common species of Northern Europe. I reproduce his figure 
(Fig. 167), which represents an unfinished web of this species 
seen in France. It shows the central part still occupied by the 
preliminary spirals or scaffolding, while the outer part is covered 
with curled threads, and the smooth spirals cut away (or not yet inserted), 
leaving thickened spots or ribbons on the rays. In the finished web most 
of the spirals pass regularly around, but the outer ones are often more or 
less irregular, as in Epeira webs, according to the shape of the space in 
which the web is made. 
According to this author, Uloborus, after inclosing her eggs in the co- 
coon, becomes careless about her web, 
and repairs it only enough to keep the 
cocoons in place, so that many imper- 
fect and irregular webs are found at 
the cocooning season. The only web Fic, 166. Curled thread of Clubiona. 
of Uloborus plumipes seen by Emerton VERSE vere 
was imperfect from the above cause, but was evidently the remains of a 
nearly round web, the rays meeting somewhat nearer the upper than the 
lower edge. 
Calamis- 
trum and 
Cribellum 
Huropean 
Species. 
dia! ek ee 
