CHAPTER XII. 

 THE HAY SPIDER AND HER SNARE : ACTINIC ORB. 



In the vicinity of Pliiladelphia, June 14tli, 1881, I found a number 

 of spiders grouped not far from each otlier on orbicular webs, whicli 

 proved to be of a type previously unknown, and which I called the Ac- 

 tinic or Ray formed orbweb. At the time of my discovery 

 p ... I considered the spider new to science, and gave it the name 

 of Epeira radiosa in a paper containing a careful and detailed 

 description of its spinning habit. ^ I then intimated that it would prob- 

 ably be assigned to a new genus, and subsequently in a verbal communi- 

 cation proposed for it the name Actis radiosa. Emerton, in his monograph 

 of the New England Epeiridse, created for the s})i(ler the genus Micro- 

 epeira. ^ 



Subsequent investigation led me to believe that the spider belongs to 

 Cambridge's genus Theridiosoma,^ and probably is identical with the 

 European form Theridiosoma gemmosum of L. Koch.* This genus has 

 marked resemblances to Epeira, as Cambridge himself allows ; and on the 

 ground of structure appears to be at least equally related to the Epeiroids. 

 .Count Keyserling, however, in his extended and admirable monograph 

 of the American spiders,^ retains the species among the Retitelarite, where 

 it had previously been placed. 



But the spinningwork shows conclusively that it must be placed with 

 the Orbitelarise. To that position, therefore, I have assigned it,*^ and it 

 becomes necessary to transfer the genus Theridiosoma from the Retitelaria} 

 to the Orbitelaria), and to make for it a new family, for which I have 

 proposed the name Actinse.' The systematic position and relations of the 



' I'loceed injurs Academy Natural Sciences of Philadelphia, 18S1, pages 163-175. 



2 Trans. Conn. Acad., Xoi. VI., 1884, page 320. 



^ Kcv. O. Pickard-Cainlx'idge. Theridiosoma argentcolnin : Annals and ^lagazino of 

 Natural Ilii^tory, 1S79, jtage lit:?. 



■* Theridium gemmosum: Verzciihniss iKt l)ci XurnluTi: lu-nli. Artcn, page 00. 



''Die Spinnen Amerikas: Theridiida', von (iraf I'"-. KcvM'iling, Zweitor Uand. page 218. 



^ Pnu'eed. Acad. Xat. Sci.. Pliila., ISSi), page ISO. "Note on the True Sy.xtematic Position 

 of the Hay Spider." 



' Actis, n/iWf, a rav. 



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