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 jioint which others, perhaps, may be able to 



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



eve op- gyj^jgg q£ originating a fixed habit from such an accidental 

 niGnt 



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 

 liorizontal 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,^ is one of the most beautiful of our indigenous sj^ecies, 



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



all the characteristics 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. 



Orchard 

 Spider. 



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

 Emerton, " New England Epeiridfe," page 333. ' 



