224 Mr. Blackwall on the Mammulse of Spideis 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 calamiiitrum *. Having detected the connexion subsisting between 

 the new spinners and the calamistrum, I confidently anticipated that spidera 

 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 extguus, Blackw. MS., which, together with Cluhiona 

 atrox, are the only species at present known to have the metatarsal joint of the 

 posterior legs furnished with the curling apparatusf. 



Thus it appears that spiders provided with calamistra have eight spinners ; 

 and as it has been demonstrated that the superior mammulse, though modified 

 in form, always perform the office of spinners, it follows that spiders with six 

 mammulae, comprising much the greater number of genera, and those with 

 four mammulee, constituting a few genera only, Mygale and Oletera, for 

 example, have precisely as many spinners as mammulae. 



A small, conical, hairy process resembling a mammula, on which, however, 

 I cannot discern any papillae, occurs at the base of the inferior spinners in 

 various species belonging to the genera Epeira, Tetragnatha, Linyphia, fValck- 

 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. 



t Researches in Zoology, p. 275, 338. 341. 



