564 PROCEEDINGS OF THE ACADEMY OF [Dec, 



surface. The special cases observed of cocoon-nest construction, 

 and of cocooning, were the following. $ 1519 made a thin nest on 

 28 June, and during the night made it very thick-walled with a narrow 

 aperture at one end. On the following day she was found at 12.30 P.M. 

 spinning vigorously across a vertical circular area, of greater diameter 

 than her own length, of the inner surface of the nest ; this was a distinct 

 cocoon-base made upon the wall of the nest. She ceased suddenly 

 at 1.10, rested quietly until I left at 1.30, and on my return at 2.50 

 was again spinning on the circular base, and worked through the 

 afternoon. At 8.10 P.M. she oviposited upon the base, holding her 

 head down and her feet on the margin of the base. She remained 

 quiet until 8.32, when she began to spin the cover for the eggs, swinging 

 the spinnerets from side to side and revolving her position from time 

 to time; this cover-spinning continued to the next day after 7 A.M. 

 On the 30 June she left the nest for the first time, from 8 July on left" 

 the nest daily to hunt for food and made a second aperture for egress. 

 The young began to leave the nest on 15 August, and at that time I 

 found a second cocoon containing eggs within the nest (the young of 

 which hatched 12 September). 9 1521 laid a mass of eggs within a 

 thin-walled nest on 2 July, but she ate them. On the 26 and 27 July 

 she worked continuously spinning a perfectly closed cocoon-nest in 

 an upper corner of the cage, then from 3 P.M. on for three hours spun 

 a cocoon-base within it, this base spun in an oblique position and its 

 diameter somewhat less than her own body length. She oviposited 

 about 9 P.M. (during my absence). Next morning at 8.00 she was 

 spinning a cover, but it was still very thin; consequently there must 

 have been a long pause between the oviposition and cover-spinning. 

 She did not leave the nest until fourteen days later; and when I opened 

 the nest on 12 September it contained hatched young. 9 1525 was 

 found on 17 July spinning a cocoon-base within an entirely closed, 

 thick nest from 3-5 P.M. ; this base was vertically inclined, extending 

 from the floor to the roof of the nest, not against its side. She rested 

 quietly for an hour and a quarter, spun again on the base for ten 

 minutes, then occupied eleven minutes in oviposition. Then she 

 seemed exhausted, and not until 10.34 began the cover-making, which 

 was completed next morning. She did not leave the nest until seven 

 days later. On 26 August she had again closed the nest, probably to 

 make another cocoon. On opening the nest 12 September I found that 

 only two eggs of the first cocoon had hatched, and none of the second. 

 These cases are given somewhat in detail, for they illustrate a con- 

 siderable range of individual difference. The cocoon-nests are viscid 



