1881.] 



NATURAL SCIENCES OF PHILADELPHIA. 



169 



Precisely the same action characterizes the Ra}^ spider. Her 

 ordinary position, or at least the one in which I most frequently 

 observed her, is a sitting posture, back upward, as shown at fig. 1. 

 The axes of the rays are held in the third and fourth pairs of legs, 

 the fourth commanding the upper, the third the lower series, 

 quite habituall^^, as it appeared to me. A sort of " basket," or 

 sj'stem of connecting lines, shown at figs. 1, 9, unites all the feet, 

 seeming to converge toward the fore-feet (perhaps, upon the second 

 pair), where they grasp the trap-line. It is upon this foot- 

 basket that the spider sits when her net is bowed. 



This, however, is not the invariable posture ; in the reconstruc- 

 tion of the raj^s and shifting of the axes, as the day's work tells 



Fig. 7,— Triangle spider, Hyptiotes cavaia, with slacli-line uncoiled and snare relaxed. 



upon the snare, the spider will A^ary her posture to that of fig. 5. 

 The trap-line generall}- has a direction downward rather than 

 upward, so that the head and fore-feet tend to be depressed below 

 the abdomen, and this depression may gradually result in the 

 complete inversion of the animal, fig, 5, so that she assumes the 

 natural position of orb-weavers. I have even seen individuals 

 with the back turned downward, fig. 8, as is the habit with the 

 Triangle spider and with all those species who make a dome or 

 horizontal orb-web, as the Basilica spider, E. basilica McCook, 

 and the Orchard spider, E. hortorum Hentz. 



If now the feet of the spider be careful I3' examined with a good 

 glass, a coil of slack-line will be seen, precisely as in the case of 

 the Triangle-si^ider. This is illustrated at fig. 8, where a, b, c, are 

 the axes of several rays, grasped in the third (3) and fourth (4) 



