192 Transactions. — Zoology. 



generally as a single one united tliroughout its whole length, and occupying a 

 transverse position in front of the rest. It is but lately that spiders have 

 been observed with two spinners only (" Spiders of Palestine and Syria," by 

 0, P. Cambridge, Proc. Zool. Soc, 1872, p. 260 j also, An. N. H., 1870, 

 pp. 414-417, ibid.) 



The spinners vary greatly in size and structure, as well as in number, but 

 hitherto their use in classification has not been what one might have expected 

 from so essential and important a portion of structure. The fourth pair of 

 spinners, when present — which it is in both sexes — is correlated, but only in 

 the female sex, with the peculiar double series of closely-set curved bristles 

 (mentioned above) on the metatarsi of the fourth pair of legs. Mr. Blackwall 

 has given the appropriate name of calamistrum to this series of bristles, and 

 has proved that their function is to card or tease a peculiar kind of adhesive 

 silk secreted and emitted from the fourth pair of spinners — the use of the 

 silk is for disposal about the spider's snare, rendering the entanglement of its 

 prey the more speedy and certain. Immediately above the spinners is a small 

 nipple-like pi-ominence, of greater or less size, which indicates the orifice of the 

 anus (f \5p). 



As it does not enter into the design of this short introduction to go into 

 the anatomical details of the Araneidea, it remains only to touch briefly upon 

 their distribution and habits, and to make a few observations on their capture 

 and mode of preservation. 



It should, howevei', be noticed here that the sexes of spiders, though not 

 generally presenting any great difference in size, yet in very many cases show 

 it to an extreme extent. The male is nearly always the smallest, though its 

 legs are often much the longest, but with many of the Epeirides and Thomisides 

 the male is scarcely more than an eighth or a tenth of the length of the 

 female. This is a fact to be borne in mind, otherwise the male of many such 

 spiders will be overlooked, or thouglit to be of a different species, while, if it 

 is remembered, the collector may often have an opportunity of noting import- 

 ant circumstances in the economy of spiders which at first sight may seem to 

 be unconnected with each other ; and thus spidei'S now perhaps described as 

 totally different species may be found to be the different sexes of the same. 



In determining the species of spiders it is very convenient to obtain 

 comparative dimensions from different portions of structure ; thus the position 

 of the eyes on the fore part of the caput furnishes us with the facial sjmce 

 (f. 5e, and 19«), and the cly2oeus (f. 3w, and 196). The comparative extent of 

 these parts is of great importance as a specific character, and they are of easy 

 observation ; that part of the facial space occupied by the eyes is concisely 

 expressed by the " ocular area" (f. 3o). 



