HORIZONTAL SNARES AND DOMED ORBS. 



151 



Such are the facts in the case. Whether this accidental tendency on 

 both sides to vary the habitual position of the snare may have laid the 

 foundation upon which has been developed the permanent habit which we 

 are now to consider, is a point which others, perhaps, may be able to 

 settle, to their own satisfaction at least. To my mind, the diffi- 

 evelop- cu iti es O f originating a fixed habit from such an accidental 

 variation are so formidable that they seem practically insur- 

 mountable. In ad- 

 dition to these is 

 the difficulty of ex- 

 plaining why the 

 same accidental va- 

 riation, appearing 

 with equal frequen- 

 cy in many species, 

 should have suc- 

 ceeded in fixing it- 

 self upon a few 

 species alone? 



In the United 

 States the spiders 

 which habitually 

 are found upon 

 horizontal snares 

 are Argyroepeira 

 hortorum, Epeira 

 gibberosa, and the 

 various species of 

 the genus Tetrag- 

 natha, and the sev- 

 eral species of Uloborus. For reasons which 

 will hereafter be explained I do not include 

 the last named species within the group to 

 be described in this chapter. 



Argyroepeira hortorum, or the Orchard 



spider of Hentz, 1 is one of the most beautiful of our indigenous species, 



. presenting in its varied green, yellow, and metallic silver colors 



Spider a ^ * ne cnarac t e ristics of some of the brightest tropical species. 



It is widely distributed, probably throughout the entire United 



States, and is thus equally at home in the cold climate of New England 



and the winterless regions of the South. Its web is usually found in low 



FIG. 141. Varied orbs of a colony of 

 spiderlings. 



1 Epeira hortorum Hentz, " Spiders of the United States ; " Argyroepeira hortorum 

 Emerton, " New England Epeiridse," page 333. 



