the Mammule employed by Spiders in the Process of Spinning. 223 
ranus, Audouin, and other skilful zootomists, who have failed to detect the 
papillæ, to regard the superior mammulæ, 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 labyrinthica, 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 18344. 
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 according to the office 
which the superior mammule 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 papillæ are situated at its extremity, assert that 
all spiders have two or four spinners; others, who regard the superior mam- 
mulz as feelers only when the terminal joint is considerably elongated and 
the papillae 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- 
mule, 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 mammulæ 
in certain species. 
The newly-discovered mammulæ 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 specinens. I may remark, that they are shorter, and further 
removed from the anus than the other mammulæ, 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 1833, p. 445. 
f Researches in Zoology, p. 298, et seq. 
262 
