The Collaborative International Dictionary of English v.0.48:

Notodontian \No`to*don"tian\, n. [Gr. nw^ton the back + 'odoy`s,
   'odo`ntos a tooth.] (Zool.)
   Any one of several species of bombycid moths belonging to
   Notodonta, Nerice, and allied genera. The caterpillar of
   these moths has a hump, or spine, on its back.
   [1913 Webster]