the Mammulse employed by Spiders in the Process of Spinning. 223 



ranus, Aiulouin, and other skilful zootomists, who have failed to detect the 

 papillae, to regard the superior mammulse, thus modified, as anal palpi, and to 

 deny that they perform the office of spinners ; an opinion in which they are 

 followed by the most eminent arachnologists of the present day. A rigorous 

 examination of these parts during the exercise of their function by living spe- 

 cimens of Agelena lahyrinthica, led me six or seven years ago to a correct 

 knowledge of their external organization ; a discovery which was published 

 in 1833*, and republished in 1834t. 



The intermediate spinners, when limited to a single pair, are usually biarti- 

 culate, and sometimes, with the inferior spinners, have their basal joints con- 

 nected or inclosed in a common envelope. 



Spiders are stated to have two, four, or six spinners accoi'ding to the office 

 which the superior mammulse are supposed to perform. Some observers, who 

 believe them in every instance to be anal palpi or feelers, even where the ter- 

 minal joint is short and the papillse are situated at its extremity, assert that 

 all spiders have two or four spinners ; others, who regard the superior mam- 

 mulse as feelers only when the terminal joint is considerably elongated and 

 the papillse are arranged along its inferior surface, estimate the number of 

 spinners with which spiders are provided at two, four, or six ; while those 

 observers, who admit the fact that silken lines are emitted from all the mam- 

 mulse, conclude that every spider has four or six spinners. I have already 

 expressed my own conviction that spiders have four, six, or eight spinners ; a 

 conviction induced by the recent discovery of an additional pair of mammulte 

 in certain species. 



The newly-discovered mammulse were first noticed by me about the year 

 1828, on inspecting the spinning apparatus of Clubiona atrox ; but I was quite 

 ignorant of their true character at that time, and only obtained a satisfactory 

 knowledge of it last autumn by a patient investigation of their external struc- 

 ture in living specimens. I may remark, that they are shorter, and further 

 removed from the anus than the other mammulse, being situated at the base 

 of the inferior intermediate pair, by which they are almost concealed when in 



* Report of the Third Meeting of the British Association for the Advancement of Science, held at 

 Cambridge in 18.^3, p. 445. 



t Researches in Zoology, p. 298, et seq. 



2 G 2 



