No. 503] THE ACTIVITIES OF ARANEADS 



701 



The absolute size of the snare and the number of spiral 

 loops vary much in individuals of the same species. The 

 size is dependent upon two factors: (1) size of the space 

 in which the web is spun, and (2) amount of silk avail- 

 able. If confined in a cramped place the spider spins no 

 snare at all, as I found by attempting to induce them to 

 spin in cages made of two panes of window glass sep- 

 arated by a wooden rim 3 cm. thick. Then if successive 

 webs are destroyed soon after making- each contains fewer 

 parts than its predecessor, which can be ascribed only to 

 deficiency of silk. Thus with one adult female of 

 sclopetaria her first snare had 21 radii, 35 spiral loops, 

 and a diameter of 37 cm. ; this I destroyed, and her second 

 made a day or two later had 17 radii, 25 spiral loops and 

 a diameter of 30.5 cm. ; a week later I destroyed this and 

 she made a third with 18 radii, 25 spiral loops and 

 diameter of 24.1 cm., then (after demolition of this one) 

 a fourth with 19 radii, 19 spirals and diameter of 23 cm. 



In orbs of adult females, particularly of marmorea, the 

 space between neighboring spiral loops varies greatly 

 in size, whence it follows that the diameter of the orb is 

 no index of the number of spiral turnings, and that differ- 

 ent females must use different parts of the body as a 

 measure of this space. This is really the most marked 

 variation to be found in orbs, and it is shown just as 

 well in those of spiderings. 



2. The Snares of Male Aegiopids and the Number op 

 Males 



In this conjunction I wished to compare the spinning 

 activities of males of Epeira marmorea and E. sclopetaria 

 with those of their females. On this matter McCook has 

 to say: 4 



As a rule, the spinning abilities of male spiders. ;is far as they relate 

 to the capture of prey, have been shown in Volume I to be less decided 

 than with females. Tbe rule is not absolute for all species, as in 

 some cases the snare spun by the male is precisely like that woven by 

 4 L. c, ?, p. 65. 



