We have seen, Can. Ent., xix., p.156 et seq., that the Bombycidæ, or Spinner Moths, are characterized, as a whole, by their short, pecitnate antennæ, ample, velvety wings, thich bodies, small heads and sluggish habit, while the pupa is usually contained in a cocoon made by the caterpillar in its last stage. To almost all these characters the sub family groups offer exceptions, and we have seen that while Dr. Packard follows the tradition of Harris, Latreille and Linneaus, modern German writers break up the family into independent groups limited by structural features taken from the imago.