TARSAL-COMB IX SPIDERS. 170 



curved bristles situated on the upper side of the metatarsal (or 

 penultimate) joint of the fourth (or hind) pair of legs. These 

 instruments, used in conjunction with an extra pair of spinners 

 (and their accompanying internal silk-glands), provide a very 

 finely fibrous, white, woolly silk, which is laid over the webbing 

 for the purpose of physically bamboozling any unfortunates who 

 may fall in. 



These short remarks have been made to show how important 

 the development of the tarsal-claws are for purposes of classifica- 

 tion ; not indeed in many cases of primary or even of secondary 

 importance, but, at all events, forming an element that must by 

 no means be overlooked, more especially when we recollect that 

 habit, circumstances, and capabilities of development react con- 

 tinuously, the one upon the other, to form decided and important 

 modifications in structure, thus rendering it necessary, when 

 attempting to classify members of such an order as the x\raneida, 

 to take into consideration their peculiar mode of life and living, 

 together with the influence it has upon their physical development 

 as well as to refrain from omitting to consider modifications in 

 structure (however subsidiary they may seem) with their bearing 

 upon the habits and capabilities of those individuals which exhibit 

 such, and consequently upon their position in systematic 

 arrangements. 



The mention of the calamistrum brings us at once to the 

 immediate subject-matter of this paper. While investigating the 

 habits of a member of the genus Theridioii^ of the family 

 Therididce (the members of which construct a mazy, indefinite 

 snare of interwoven, crossing lines ; or else a horizontal sheet-like 

 web), and having for the purpose of observation, specimens of 

 both sexes in confinement, we were attracted by a peculiarity we 

 had not before noticed in the construction of the snare. 



When at large, this species, Theridion feptdarioruni, C.L.K., 

 constructs in our hot-houses — for in these comfortable (quarters 

 alone the species thrives — in this ungenial clime, large snares, often 

 two feet in height, consisting of scattered upright lines, interwoven 

 with cross lines attached to the uprights at all angles, and fixed 

 to neighbouring convenient objects. 



Now, it has ever been a matter of surprise to us, for we have 



