170 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



extended upward from the exterior of the dome to the inclosing and sup- 

 porting labyrinth of crossed lines. Evidently the little engineer had com- 

 pleted the work, so well begun in the depression of the edges of her orb, 

 by elevating the central part through the same method of applying force, 

 but in an opposite direction. So well had the power been graduated that 

 the proportions of the dome were beautifully preserved. 



We have thus traced the analogy between the spinningwork of this 

 species of Orbweavers and that of Lineweavers in these several particulars: 

 First, in the dome shaped snare and dwelling place, which cor- 

 Spmnmg-- responds with that made by a species of the Retitelarian genus 

 . , Linyphia. Second, in the mass of intersecting lines placed around 



g-ies. '^^^^^ above the dome, which is the characteristic web of the Retite- 



larian genus Theridium and of many other genera. Third, in the 

 sheet like curtain beneath the dome, which in form resembles the thiidy 



Fig. 159. Position of Basilica's web after the horizontal orb has been transformed. The mesKed 

 structure is only indicated. The original plane of the orb is shown at f. 



sheeted web of many species of Linyphia, as, for example, L. costata ; and 

 which in both position and form corresponds with the underlying curtain 

 or dish of L. communis and L. marginata. 



Thus, Epeira basilica is seen to possess all the leading characteristics of 

 the principal families of the Retitelarian, namely, (1) the maze of crossed 

 lines, and (2) the sheeted web in exact detail, and (3) the dome shaped 

 web in outline. It also possesses the chief characteristic of the Orbitelaria?, 

 namely, the geometric web, or radiating lines regularly crossed by concentrics. 

 Moreover, it combines in its dome structure the vertical and horizontal forms 

 which arc the prevailing ones in the orb of its congeners. The Basilica 

 spider may, therefore, be regarded as well nigh, if not completely, bridging 

 the space between the spinning economy of these two great tribes of the 

 Araneije. 



