and (Economy of the Arancidea. 223 



Four, six, or eight mammulae, somewhat conical or cylindrical in 

 figure, and composed of one or more joints each, constitute the ex- 

 ternal spinning apparatus of the Araneidea : they are usually closely 

 grouped in pairs at the extremity of the abdomen, and are readily 

 distinguished from each other by their relative positions. The pair 

 situated nearest to the anus may be denominated the superior spin- 

 ners ; that furthest removed from the anus, the inferior spinners ; 

 and the mammulae placed between these extremes, the intermediate 

 spinners ; distinguishing them, when there are two pairs, by prefixing 

 the terms superior and inferior. Exceedingly fine, moveable papillae 

 or spinning tubes, for the most part dilated at the base, occur at the 

 extremity of the mammulae, or are disposed along the inferior surface 

 of their terminal joint, whence issues the viscous secretion of which 

 all the silken lines produced by spiders are formed. The papillae 

 connected with the mammulae vary greatly in number in different 

 species of spiders, and also differ considerably in size, not only in 

 individuals of the same species, but often even on the same mam- 

 mulae. 



Among our native spiders, the larger species of Epeircc have the 

 mammulae most amply provided with papillae ; it is probable, how- 

 ever, that the total number does not greatly exceed a thousand even 

 in adult females of Ep'eira quadrata, whose weight is about twenty 

 grains, and in many other species it is much smaller. In Tegenaria 

 civilis the total number of papillae does not amount to four hundred ; 

 in Textrix lycosina and Clubiona corticalis it is below three hundred; 

 in Segestria senoculata it scarcely exceeds one hundred ; and in many 

 of the smaller spiders it is still further reduced. 



A difference in the number and size of the papillae connected 

 with the several pairs of mammulae in the same species, and with 

 similar pairs in different species, is also very apparent. In spiders 

 of the genera Ep'eira., Tetragnatha, Linyphia, Theridion and Se- 

 gestria, they are generally much more numerous and minute on the 

 inferior spinners than on the superior and intermediate ones ; the 

 last are the most sparingly supplied with them, and in the case of 

 Segestria senoculata each has only three large papillae at its extre- 

 mity. An arrangement nearly the reverse of this takes place in some 

 of the Drassi, and is conspicuous in Drassus ater., which has the 

 intermediate spinners abundantly furnished with papillae, those on 

 the inferior spinners being very few in number and chiefly of large 

 dimensions, emitting the viscous secretion copiously. The papillae 

 connected with the short terminal joint of each inferior spinner of 

 this species vary in number with the age of the animal ; the young, on 

 quitting the cocoon, are provided with four only ; individuals which 

 have attained nearly a third of their growth have five or six ; those 

 about two-thirds grown, six or seven ; and adults, which have ac- 

 quired their full complement, eight ; two of them, situated on the 

 inferior surface of the spinner, at a greater distance from its extre- 

 mity than the rest, are minute and almost contiguous. It is a fact 

 deserving of notice, that the papillae are not always developed simul- 

 taneously on these spinners, six, seven, or eight being sometimes ob- 



