326 OBSERVATIONS ON THE 
if in air; while others have not survived for a single 
hour. It is evident, therefore, from these curious 
facts, that some Spiders possess the power of extract- 
ing respirable air from water; for though, in the act 
of submersion, the branchial stigmata are usually 
enveloped in a bubble of air, yet so small a supply is 
speedily exhausted, and, indeed, soon disappears. 
The external and internal organization of such 
species of Araneidea as can exist for a long period of 
time under water deserves to be attentively examined ; 
but those species which I have observed hitherto are 
minute, and it would require the hand and eye of an 
accomplished anatomist, assisted by the most delicate 
instruments and powerful magnifiers, to effect this 
desirable object satisfactorily. 
Instances of long-sustained abstinence from food 
by animals of the order Araneidea, unaccompanied by 
any manifest diminution of vital energy, have been 
recorded by various naturalists, and many more might 
easily be added to the catalogue ; I shall limit myself, 
however, on the present occasion, to the narration of 
a very remarkable case, in illustration of this fact, 
which came under my own immediate observation. 
A female Zheridion quadripunctatum, captured in 
the month of August 1829, was placed in a phial of 
transparent glass, and fed with flies till the 15th of 
October in the same year, during which interval she 
accomplished her final moult, and arrived at maturity. 
She was then removed to a smaller phial, which was 
