Source : Webster's Revised Unabridged Dictionary (1913)

Regularia \Reg`u*la"ri*a\ (r[e^]g`[-u]*l[=a]"r[i^]*[.a]), n.pl.
   [NL.] (Zo["o]l.)
   A division of Echini which includes the circular, or regular,
   sea urchins.