the Mammulæ employed by Spiders in the Process of Spinning. 221 
quadrata, whose weight is about twenty grains, and in many other species it 
is much smaller. Each of the six mammule, in every living Epeira whose 
spinning apparatus I have attentively inspected, has presented one or more 
papillz decidedly larger than the rest, which uniformly occupy the same re- 
lative situations in individuals identical in species; but I have not yet been 
able to satisfy myself what especial purposes they subserve. 
Wishing to determine by experiment the strength of a line by which a female 
Epeira diadema, weighing ten grains, had suspended itself from a twig, I at- 
tached to its extremity a small square piece of muslin with the corners nearly 
drawn together, so as to form a minute sack, into which I carefully introduced 
sixty-one grains in succession, being rather more than six times the weight of 
the spider, before it broke; but on the addition of half a grain more it gave 
way. 
In several species belonging to the genus Tegenaria of Walckenaer, in 
Tegenaria domestica and Tegenaria civilis, for example, the total number of 
papilla does not amount to four hundred; in Textrix agilis, Blackw., Lycosa 
saccata, and Clubiona corticalis, it is below three hundred; in Walckenaera* 
acuminata, Blackw., and Segestria senoculata, it scarcely exceeds one hundred ; 
and in many of the smaller spiders it is still further reduced. 
A difference in the number and size of the papillæ connected with the seve- 
ral pairs of mammulæ in the same species, and with similar pairs in different 
species, is also very apparent. In the spiders constituting the genera Epeira, 
Tetragnatha, Linyphia, Theridion, Segestria, and many others, they are gene- 
rally much more numerous and minute on the inferior spinners than on the 
superior and intermediate ones; the last are the most sparingly supplied with 
them, and in the case of Segestria senoculata each has only three large papillze 
at its extremity. An arrangement nearly the reverse of this takes place in 
some of the Drassi, and may be advantageously seen in Drassus ater. "This 
species has the intermediate spinners abundantly furnished with papillze, those 
on the inferior spinners being very few in number and chiefly of large dimen- 
sions, emitting the viscous secretion copiously. For the purpose of deter- 
mining bow many papillz are connected with the short terminal joint of each 
* This generic name, which, through my own inadvertency, has hitherto been printed Walckenaeria, 
is now corrected. 
VOL. XVIII. 26 
