OHAPTEE IX. 

 HORIZONTAL SNARES AND DOMED ORBS. 



I. 



THE Orbwebs heretofore considered all belong to the general division 



described as vertical orbwebs. The snares to be considered in this chapter 



are known as horizontal orbs. The horizontal orbweb in all es- 



p^ 1111 sential particulars is woven like the vertical orb and differs chiefly 



berosa m the fact that it is usually hung wholly or partly in a 



horizontal position. 



In the species making vertical webs, the habit is so firmly fixed that 

 the spiders rarely deviate therefrom, and never, except under circumstances 

 which constrain a departure. Nevertheless, it is interesting to remark that 

 sometimes they do spin orbs that more or less approximate the horizontal. 

 Occasionally these orbs are entirely horizontal. For example, I have 

 known a brood of young Epeira sclopetaria, freshly escaped from the co- 

 coon, to spin upon the same object minute orbs, some of which were ver- 

 tical, while others were as truly horizontal as though they had been made 

 by a species that habitually weaves an orb of that sort. Fig. 141. It was 

 not difficult for me to determine that these individuals were influenced to 

 an abnormal act by the conditions under which they wrought. It was 

 comparatively easy for them to get foundation lines so placed that a hori- 

 zontal web almost inevitably resulted ; while, on the other hand, 

 Varia- the frames for a vertical web could not have been obtained 

 ti^C/b exce Pt w ith the greatest difficulty. Yet, in the case of a few of 

 Plane. the same brood nearly as great difficulties were overcome, and a 

 vertical web was made. For example, the little fellows in the 

 cut (Fig. 141) found it easy to weave an orb horizontally around the metal 

 frame that supports the lamp chimney, and this they did. But others fol- 

 lowed the specific habit and sent down lines to the table, making a 

 triangular frame and a vertical orb within it. 



So, too, it may be said that spiders which make horizontal snares are 

 sometimes constrained by difficulties of the site chosen to deviate more or 

 less from the horizontal plane. Indeed, I have seen the orb of Tetrag- 

 natha inclined at almost every angle, and occasionally have found it spun 

 jn an absolutely vertical position. 



(150) 



