CHAPTER XII. 
THE RAY SPIDER AND HER SNARE: ACTINIC ORB. 
I, 
In the vicinity of Philadelphia, June 14th, 1881, I found a number 
of spiders grouped not far from each other on orbicular webs, which 
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 
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.1 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 Epeiride, created for the spider 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 Retitelariee, where 
it had previously been placed. 
But the spinningwork shows conclusively that it must be placed with 
the Orbitelariw. To that position, therefore, I have assigned it,® and it 
becomes necessary to transfer the genus Theridiosoma from the Retitelarie 
to the Orbitelarie, and to make for it a new family, for which I have 
proposed the name Actine.? The systematic position and relations of the 
* Proceedings Academy Natural Sciences of Philadelphia, 1881, pages 163-175. 
? Trans. Conn. Acad., Vol. VI., 1884, page 320, 
* Rey. O, Pickard-Cambridge. Theridiosoma argenteolum: Annals and Magazine of 
Name and 
Position. 
' Natural History, 1879, page 193. 
*Theridium gemmosum: Verzeichniss der bei Nurnberg beob. Arten, page 69. 
* Die Spinnen Amerikas: Theridiide, von Graf E. Keyserling, Zweiter Band, page 218. 
* Proceed. Acad. Nat. Sci., Phila., 1889, page 180. “Note on the True Systematic Position 
of the Ray Spider.” 
7 Actis, axric, a ray. 
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