CHAPTER XL 

 THE TRIANGLE SPIDER: THE ORB SECTOR. 



I. 



THE snare of Hyptiotes cavatus, the Triangle spider, has awakened 

 deep interest among naturalists on account of its peculiar construction and 

 manner of operation. The little spinner is equally interesting to the sys- 

 tematist, because of its relation to other individuals of its tribe; and in- 

 deed because of the question, which has divided arachnologists, as to what 

 tribe in the order Araneee it truly belongs. 



I have no hesitation in assigning it to the Orbitelarise, where it seems 

 to me that its spinningwork undoubtedly requires it to be placed. On the 

 grounds of structure, also, I follow Dr. Thorell and give it the 

 ys em- game position, 1 although it must be allowed that the authorities 

 are well worthy of consideration who place it among the Clubi- 

 onidse. As in the case of Uloborus, this is done almost exclusively upon 

 the grounds that Hyptiotes possesses the cribellum, a special organ for the 

 exudation of spinning material, and the calamistrum, by which such ma- 

 terial is manipulated or hackled until it presents the appearance which 

 will be further described hereafter. 



The snare is a sector of a circle, including about forty-five degrees of 

 the area, and with a radius varying from twelve to twenty inches or less. 

 It is thus, as to shape, in strong contrast with the typical orb of 

 e Epei'ra, which is a full circle, and with the sectoral orb of Zilla, 



which is a circle lacking its upper sextant, while the net of 

 Hyptiotes is just about a sextant or sixth of a circle. In the language of 

 Professor Wilder, who has pointed out these relations, to use a more 

 homely comparison, the net of Epeira is an entire pie; that of Zilla or 

 Nephila is a pie with a piece cut out; while that of Hyptiotes represents 

 the missing piece. In algebraic language, Zilla + Hyptiotes = Epe'ira. 2 

 (See Fig. 170.) 



The snare is habitually spun in a vertical plane, although it is subject 

 to some variation, and I have occasionally found it more or less horizontal. 

 It is hung in all sorts of positions between the branches of trees and 

 bushes, but its most favorite habitat appears to be pine woods. I have 



1 On European Spiders, page 69. 



2 Professor Bert G. Wilder, Triangle Spider, " Popular Science Monthly," 1875, page 653. 



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