64 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



lines, settle upon a site between the forked twigs of a bush and carry her 

 foundation lines around in the manner described. But, on the other hand, 

 I arn prepared to say that the air laid bridge lines are also used for the 

 foundations or frames of orbs. The following are my reasons for this 

 opinion : 



1. First, the hours in the evening at which the greatest activity of web- 

 weaving begins are those in which also begin the formation of the bridge 

 lines. The latter action quite invariably precedes the former. 



2. Again, a study of the foundation lines of very many webs has given 

 me almost conclusive evidence that they must have been laid by the aid of 



air currents. For example, the webs of some species, as Acrosoma 



Webs mitrata, A. spinea, and A. rugosa, are frequently found strung be- 



re c e j. ween young trees separated by two or three yards of space. That 



Trees these builders might have dropped to the ground, crept over the 



wood, grass, or dry leaves carrying the thread in the free, out- 

 stretched claw is, perhaps, not impossible, but does not seem to me at all 

 probable, although short spaces over smooth surfaces might be passed in 

 this way. I once found an orb hung upon lines which stretched from the 

 balustrade of a bridge that spans a deep glen in Fairmount Park, to the 

 foliage of a tree that springs out of the glen at least twenty-five feet below 

 the bridge. Unless the foundations of this orb were formed by line bridging 

 the interspace of a yard or more, it must be inferred that the spider had 

 dropped from the balustrade to the glen, crossed the interval to the trunk 

 of the tree, ascended it, and, having made a detour of nearly sixty feet to 

 the point directly opposite that from which she started, all the while car- 

 rying her line with her and keeping it free from entanglement, have drawn 

 the line taut and so completed her foundation. Such a supposition could not 

 well be entertained, and it is clear that a breeze carried the line across from 

 the spider's spinnerets. 



I have noticed stronger examples of circumstantial evidence. Very many 

 webs of Tetragnatha extensa and T. grallator have been seen spread upon 

 bushes overhanging pools and streams of water; others were stretched be- 

 tween separated water plants or from such plants to the shore. (See Fig. 60.) 

 Either the foundation lines were borne by air currents, or the spiders must 

 have crossed upon the water, carrying their lines. The latter supposition is 

 not wholly untenable, but will hardly be raised by any one who has 

 studied the spinning economy of the creature. 



One other example may be cited. At Atlantic City, by the boat- 

 landing where pleasure boats used for sailing upon the Inlet are stored, 



there is (or was) an immense colony of Epei'roids, chiefly Epeira 

 Orbs over s t r i Xj E sclopetaria, and E. benjamina (domiciliorum Hentz). 



During the summer months of 1880-81. great numbers of these 

 spiders had their lines strung between the opposite exterior walls of the 

 boat houses, which were built upon piles driven into the water. These 



