and CEconomy of the Araneidea. 237 



tain ; consequently, cases 4, 5 and 6, which present instances of an 

 odd number of eyes disposed irregularly, would be regarded at all 

 times with suspicion ; as no such objection, however, can be urged 

 against case l,a solution of the difficulty it presents must be sought 

 for in a more accurate acquaintance with the species. 



Interesting chiefly in a physiological point of view, cases 3 and 7 

 show that a liability to irregularity in structure is not limited to the 

 eyes, and that those organs are subject to preternatural variations in 

 size as well as number. 



The obscurity in which the cause of these remarkable organic mo- 

 difications is involved, careful investigation, conducted upon sound 

 philosophical principles, can alone dispel*. 



Argyroneta aquatica, Dolomedes Jimbriatus, and Lycosa piratica 

 are known to descend spontaneously beneath the surface of water, the 

 time during which they can respire when immersed depending upon 

 the quantity of air confined by the circumambient liquid among the 

 hairs with which they are clothed. There are, however, some spi- 

 ders of small size, Erigone atra and Savignia frontata, for example, 

 which, though they do not enter water voluntarily, can support life 

 in it for many days, and that without the external supply of air so 

 essential to the existence of Argyroneta aquatica under similar cir- 

 cumstances. It is probable that this property may contribute to their 

 preservation through the winter, when their hybernacula are liable 

 to be inundated f. 



Spiders, though extremely voracious, are capable of enduring long 

 abstinence from food. A young female Theridion quadripunctatum, 

 captured in August 1 829, was placed in a phial and fed with flies till 

 the 15th of October, in the same year, during which period it accom- 

 plished its final moult and attained maturity. It was then removed 

 to a smaller phial, which was closely corked and locked up in a book- 

 case, its supply of food being at the same time discontinued. In this 

 situation it remained till the 30th of April 1831, on which day it 

 died, without receiving the slightest nourishment of any description. 

 Throughout its captivity it never failed to produce a new snare when 

 an old one was removed, which was frequently the case ; and it is a 

 fact particularly deserving of attention, that the alvine evacuations 

 were continued, in minute quantities and at very distant intervals, to 

 the termination of its existence]:. 



When about to deposit their eggs, spiders usually spin for their 

 reception silken cocoons displaying much diversity of form, size, co- 

 lour, and consistency. Those of the Lycosce have a lenticular, or 

 spherical figure and compact structure, with the exception of a nar- 

 row zone of a delicate texture by which they are encircled. In con- 

 structing their cocoons, these spiders slightly connect the margins 

 of the two compact portions, beneath which the thin fabric of the 

 zone is folded. This simple contrivance affords an admirable pro- 



* Annals and Magazine of Natural History, vol. xi. p. 165-168. 

 t Report of the Third Meeting of the British Association for the Advancement 

 of Science held at Cambridge in 1833, p. 446. 

 % Researches in Zoology, pp. 302, 303. 



