TRANSACTIONS OF THE SECTIONS. 445 



they had arrived at maturity, he treated in the manner de- 

 scribed in the preceding cases. In the autumn of the same 

 year these spiders deposited their eggs in cocoons spun for 

 their reception, out of which the young issued in the ensuing 

 spring, having undergone their final metamorphosis in the 

 cocoons. 



These experiments, besides effecting the purpose for which 

 they were instituted, served also to supply collateral evidence 

 of the correctness of M. Audebert's observations relative to 

 the capability of the House-spider, Aranea domestica, to pro- 

 duce several sets of prolific eggs in succession, without renew- 

 ing its intercourse with the male ; for three females of the spe- 

 cies Agelena labyrinthica deposited each a second set of eggs, 

 and a female, JEpeira cucurhitina, laid four consecutive sets, 

 intervals of fifteen or sixteen days intervening, all of which pro- 

 duced young, though these females had not associated with 

 males of their species for a considerable period antecedent to 

 the deposition of the first set of eggs. 



MM. Lyonnet and Treviranus, with other skilful zootomists, 

 have fallen into the error of mistaking the superior spinning 

 mammulas of spiders, when triarticulate and considerably elon- 

 gated, for anal palpi {palpes de Vamis), denying that they per- 

 form the office of spinners, in consequence of their having failed 

 to detect the papillae from which the silk proceeds ; and in this 

 opinion they are followed by the most distinguished arachno- 

 logists of the pi'esent day. The author is inclined to attribute 

 this singular oversight to the peculiar disposition and structure 

 which the papillae or spinning tubes connected with the su- 

 perior mammulae, when greatly elongated, frequently exhibit. 

 Arranged along the under side of the terminal joint, they pre- 

 sent the appearance of fine hairs projecting from it at right 

 angles ; but if the spinners when they are in operation be care- 

 fully examined with a powerful magnifier, the function of the 

 hair-like tubes may be ascertained without difficulty, as the fine 

 lines of silk proceeding from them will be distinctly perceived. 



In conducting this observation Mr. Blackwall usually employs 

 the Agelena labyrinthica of M. Walckenaer: its size, the length 

 of- its superior mammulae, and its habits of industry, afford a 

 combination of advantages comprised by no other British spider. 



The purpose subserved by the superior mammulae, when very 

 prominent and composed of several joints, is the binding down 

 with transverse lines, distributed by means of an extensive la- 

 teral motion, the threads emitted from the inferior mammulse ; 

 by which process a compact tissue is speedily fabricated. 



The foregoing facts supply a striking exemplification of the 



