140 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



spirals were thus drawn in shorter loops with much less curve, and the 

 centre of the hub was well toward the top, two inches therefrom. In an- 

 other adult web the orb measured eleven inches long by eight wide, the 

 number of radii was forty-one, of spirals forty-five, of notched concentrics 

 nine. The centre of the hub was five inches from the topmost spiral. 

 The following measurements give some idea of the size of Tri- 

 aranea's orb : Web No. 1, about four inches diameter ; radii 

 forty-three ; spirals thirty-five. No. 2, radii twenty ; spirals 

 twenty. No. 3, diameter six and a half inches; radii thirty-five; 

 spirals thirty-five. No. 4, seven inches long by six wide. No. 5, six and 

 a half long by five and a half wide. Radii forty ; spirals, ' forty-eight 

 below, twelve above. No. 6, forty-one radii ; forty-five spirals. No. 7, two 

 and a half by two and a half. No. 8, eleven by eight inches, central five 



inches from top, three and one-fourth from 

 side ; radii forty-one, spirals forty-five, notched 

 zone nine. 



Triaranea is frequently found in the neigh- 

 borhood of human habitations, around barns 

 and various outbuildings of farms, but also 

 loves the field, and is frequently found therein. 

 It does not appear to have in so marked a de- 

 gree as Labyrinthea a preference for nest sites 

 naked of foliage, when such can be conven- 

 FIG. i3o. The looped spirals, L.S., in iently procured. 



zma's orb. ^^g m aze or snare of netted lines in the 



web of Triaranea is, on the whole, not quite so prominent as that of Lab- 



yrinthea, but in some cases it is very heavy, and generally is decidedly 



marked in the adult spider. The variation in this portion of 



. e \f ai " the snare may be seen from the following extract from my note 



book, made during one day : No. 1, retitelarian lines not heavy ; 



No. 2, little or no retitelarian lines ; No. 3, slight retitelarian lines above ; 



No. 4, retitelarian lines quite abundant in a protecting wall behind and 



above but not before the orb. 



These, like other differences in webs, may often be accounted for simply 

 by the fact that they exhibit different stages of completion. Spiders do 

 not invariably finish secondary parts of their web at the same 

 Cause of time ^hat ^ e y g p m ^ e primary one. The nest or tent, for ex- 



ample, will sometimes be a matter of growth, .and it is probably 

 the case that the netted cross lines of composite snares are 

 developed in the same way. Young spiders also differ from adults in the 

 degree of attention which they pay to the secondary parts of their snare. 

 The principal part, however, the orb in the case of Orbweavers, is invari- 

 ably completed, if circumstances will permit it, before the spider settles 

 herself to the pursuit of prey. 



