The Collaborative International Dictionary of English v.0.48:

Araneidan \Ar`a*ne"i*dan\, a. (Zool.)
   Of or pertaining to the Araneina or spiders. -- n. One of the
   Araneina; a spider.
   [1913 Webster]

WordNet (r) 3.0 (2006):

araneidan
    adj 1: relating to or resembling a spider [syn: araneidal,
           araneidan]