224 Mr. BrackwaLr on the Mammule of Spiders in Spinning. 
a state of repose. Their figure is somewhat conical, but compressed and 
truncate, so that the base and apex are elliptical with long transverse axes. 
Consisting of a single joint only, each mammula is connected with the other 
throughout its entire length, the extremity alone being densely covered with 
exceedingly minute papillae, which emit the viscous matter that is formed into 
the pale blue bands, constituting the most important part of the snare of this 
spider, by means of the combing or rather curling instrument, which I pro- 
pose to name calamistrum*. Having detected the connexion subsisting between 
the new spinners and the calamistrum, I confidently anticipated that spiders 
provided with the latter would likewise possess the former; and such I found 
to be the case on examining Drassus viridissimus, Walck., Drassus parvulus, 
Blackw., and Drassus exiguus, Blackw. MS., which, together with Clubiona 
atrox, are the only species at present known to have the metatarsal joint of the 
posterior legs furnished with the curling apparatus f. 
Thus it appears that spiders provided with calamistra have eight spinners ; 
and as it has been demonstrated that the superior mammulæ, though modified 
in form, always perform the office of spinners, it follows that spiders with six 
mammulæ, comprising much the greater number of genera, and those with 
four mammulæ, constituting a few genera only, Mygale and Oletera, for 
example, have precisely as many spinners as mammule. 
A small, conical, hairy process resembling a mammula, on which, however, 
I cannot discern any papillæ, occurs at the base of the inferior spinners in 
various species belonging to the genera Epeira, Tetragnatha, Linyphia, Walck- 
enaera, Manduculus, &c.: what influence it exercises upon the economy of 
those spiders in which it is found remains to be discovered. 
* A description and figures of the calamistrum are published in the Transactions of the Linnean 
Society, vol. xvi. p. 473—4. tab. xxxi. fig. 2, 3. In the same volume, p. 476, an account is given 
of a strong, moveable spine inserted near the termination of the tarsus of each posterior leg, on the 
under side, in spiders belonging to the genus Epeira, which I propose to denominate sustentaculum. 
+ Researches in Zoology, p. 275, 338, 341. 
