The Collaborative International Dictionary of English v.0.48:

Periscians \Pe*ris"cians\, Periscii \Pe*ris"ci*i\, n. pl. [NL.
   See Periscian.]
   Those who live within a polar circle, whose shadows, during
   some summer days, will move entirely round, falling toward
   every point of the compass.
   [1913 Webster]