and (Economy of the Aianeidca. 237 



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

 odd number of eyes disposed irreguhxrly, woidd be regarded at all 

 times with suspicion ; as no such olyrr-tion, however, can be urged 

 against case l,a solution of tiie ditiiculty it presents must be sought 

 for in a more accurate acquaintance witli the species. 



Interesting chieHy 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 tho.-e 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 

 piulosophical principles, can alone dispel*. 



Aryijroneta acjuatica, Dolomedcs fiinhriatus., and Lycosa piratica 

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

 time during which they can resj)ire 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 utra and Suvigma frontata, for example, 

 AS hicli, though they do not enter water voluntarilj', can support life 

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

 essential to the existence o^ Aryyroncta 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 1829, 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- 



• Ani'als and Magazine of Natural History, vol. xi. p. 1G5-1G8. 

 ■f- Ueport of the Third Meeting of the British .\ssociation for the Advancement 

 of Science held at Cambridge in 1833, p. 44G. 

 X Researches in Zoology, pp. 302, 303. 



