470 SUPPLEMENT 



her prey, and to escape from the least danger, Degeer has 

 seen her with her head upwards, and the feet applied against 

 the body. 



It is easy to conceive the mode in which the argyroneta 

 introduces the air into her ball, and how she totally fills it. 

 At first the water may be supposed to occupy its interior 

 capacity. To empty it, and substitute another fluid, the animal 

 goes continually to the surface of the water, charges itself 

 with a bubble of air, transports it into its habitation, un- 

 burthens itself of its aerial provision, and displaces an equal 

 mass of water, which issues through the lower aperture. By 

 repeating this operation several times, it succeeds in expelling 

 all the water out of its cell, and introducing the same volume 

 of air. The males, as well as the females, construct for 

 themselves, at all the favourable seasons of the year, similar 

 habitations, which demonstrates the analogy existing between 

 these and the other aranei'des of the same tribe. Degeer 

 found, in the month of December, one of these balls, closed 

 in all parts, and in which the animal was, as it were, im- 

 prisoned. It issued forth through a rent made by this ob- 

 server, and immediately proceeded to suck a fresh-water 

 assellus, which he presented to it. It is probable that these 

 arane'ides shut themselves up in this manner to pass the winter. 

 The same naturalist, as well as Clerk, has preserved, in the 

 same vessel, many individuals of both sexes, without one 

 devouring the other ; and though they had been deprived, for 

 several days, of every kind of nourishment, all that passed in 

 the rencontres between male and male, and female and 

 female, was simply touching each other, or attacks which led 

 to no murderous conclusion. Thus some writers have falsely 

 attributed to the aquatic spiders, probably presuming from- 

 analogy, a cruel and voracious character, with regard to their 

 own species. 



The eggs are round, of a yellow sulphur colour, and shut up 



