1881.] 



NATURAL SCIENCES OF PHILADELPHIA. 



175 



lY. The Affinities of the Actinic Orb with other Orb Webs. 



Not the least interesting and valuable feature of the Ray- 

 spider's industry, is that it discovers a connecting link between 

 two forms of snare which stand at the very opposite poles of the 

 spinning-work of the (Orbitelarise) orb-weavers. At the one ex- 

 treme is the familiar circular snare or full orb of the ordinary 

 garden spider, as, for example, that of Epeira domiciliorum, 

 Hentz, fig. 13. At the other is the orb-sector of the Triangle 

 spider, figs. 6, 1. A glance at these will show how far they are 

 apart in structure. The same separation appears in the habits of 

 the two araneads.^ As opposed to the Hyptiotes, the spiders of 

 which E. domiciliorum is a type hang head downward in the 



Fig. 11. — Ray spider's snare 

 after usage in taking prey. 



Fig. 12.— Ray spider. Half of 

 orb eliminated and a new trap- 

 line, Tb, formed. 



centre of the orb, with their feet grasping small groups of the 

 radii ; or sit in a silken den, or crevice, holding to a taut trap-line 

 which is connected with the centre. There is no slack coil, and 

 no springing of the net as with the Triangle spider. 



The industry of Radiosa, it is now seen, is united to that of the 

 Full Orb makers (E . domiciliorum, et al.), on the one extreme, by 

 the completeness of the circle; but with that of Hyptiotes, on the 

 other extreme, by the independent character of the rays, the 

 nature of the trap-line, and the entire mode of operating the snare. 

 The facts necessary to trace their affinities I have already given. 



^ I hope that I shall be tolerated in the invention of this general word 

 for members of the Order Aranese ; "Arachnid," the class term, is too 

 general ; "aranead" is needed for the true spiders. 



