1888.] NATURAL SCIENCES OF PHILADELPHIA. 209 



glass jar. Its movements were thus entirely open to observation. 

 .-•• ,'.''■- .- .'- f Along this subterranean way or tun- 

 nel the spicier strung fine threads cov- 

 ering the bottom, the side and the top, 

 forming a frame quite resembling the 

 founds tion seaifolding used in spin- 

 ning the vertical tube. (See fig. 6). It 

 then proceeded to thicken these lines- 

 in the following manner. The bottom 

 parts were overspun by emitting from 

 the long inferior spinnerets numerous 

 ^>,.- ■ 'iirn'w, ; . fiuc threads whicli wcrc beaten down 



i' '' '' against the surface by dropping the. 



' spinnerets, and were spread around 

 by a lateral movement of the ab- 

 domen, which of course carried with 

 - . - it the spinnerets and the threads issii- 



Fig. 7. Purseweb Spider's tube. Sec- i"g thcrcform. The auimal's motiott 



tion after frame is overspun. reminded ouc of a plastcrcr usiug his 



trowel to spread mortar rather than a weaver spinning cloth. The. 

 space covered by these movements having been sufficiently thicken- 

 ed, the sjoider proceeded to another spot and went through the same 

 process. When it came to thickening the upper portion of its tube it 

 turned its abdomen upward resting its body upon the dorsum of the 

 cephalothorax. In other words the creature laid upon its back. Its 

 abdomen was well turned over so that in this position the spider was 

 almost in the form of a semicircle. The pressure of the abdomen, 

 upwards forced the lines at the point of impact into a little bay, the 

 concavity of which was thickened over with threads spun from the 

 spinnerets Avhich were managed in the way already described. That 

 is, the spinnerets were moved back and forward, and the out spun- 

 threads were beaten upwards into the lines already formed. 



This procedure very closely resembles the manner of spinning 

 which I have often observed in Mygale Hentzii the large tarantula 

 of our southwestern States. This mode of thickening over the foun- 

 dation lines of the tube also closely resembles the behavior of orb- 

 weaving and other spiders when constructing the thick padding 

 which surrounds their eggs, forming their eggsacs or cocoons. I 

 have seen it notably in the case of Lycosa. It is without doubt the 

 way in which the trap-door spider of California {Cteniza Californica,'} 



