No. 503] THE ACTIVITIES OF ARANEADS 



699 



and 35.6 cm. diameter of adult females. In other words 

 while the diameter of the orb increases nearly five times, 

 the number of spirals becomes slightly more than doubled, 

 and the number of radii are increased less than one quar- 

 ter. For E. marmorea the webs of immature individuals 

 of from .3 to .6 cm. were compared with those of adult fe- 

 males, and the table shows that between these ages the 

 number of radii remains about constant, while the num- 

 ber of spiral turns and the diameter of the spiral about 

 double themselves; females in the penultimate instar show 

 the orb almost as complex as that of females in the last 

 instar. 3 For both of the species examined, accordingly, 

 the age changes in the snare are greatest with regard to 

 the diameter of the viscid spiral, less with regard to the 

 number of its loops (on the average these only doubling 

 their number), and least with regard to the number of the 

 radii. 



It is interesting that the first snare of the spiderling 

 has all the parts of that of the adult, namely, the central 

 woven hub and the inner non-viscid spiral in addition to 

 the viscid spiral, radii and foundation lines. With in- 

 creasing age of the spider the threads of the snare become 

 thicker, the whole structure larger, but otherwise beyond 

 the addition of a few more radii and a doubling of the 

 number of the spiral turns there is no particular change 

 effected. The newly-hatched show also about the same 

 specific habits as do the adult: in marmorea the young, 

 as does the mother, remains in a nest in a curled leaf hold- 

 ing communication with the snare only by a trap-line; 

 and in sclopctaria the young, again like the mother, re- 

 mains either at the center of the snare or else away from 

 it, holding a trap-line but not hiding within a nest. Fur- 

 ther, though there are frequently imperfections in the 



