176 [March 



that corresponds to his specimen, and then continue the investigation by 

 examining the various subdivisions under it, until one is found that is 

 again descriptive of his specimen, and at last the special description indi- 

 cating the family. Whenever the catagory disagrees with his specimen, 

 he should, therefore, pass on to the next one in the same kind of type 

 until one is found that does agree with it. 



Each catagory includes everything hetiveen it and the next of the 

 same value, so that it is useless to look under a disagreeing head for 

 anything that characterizes the specimen whose structure does not corres- 

 pond to it. 



The student must be careful, in detaching the wings from the thorax, 

 of a moth, that the little " bristle," which attaches the hind wings to the 

 anterior pair, is not broken. 



HETEROCEBA. 



Antennse setaceous or fusiform vnth the apex attenuated (except Cast- 

 nia, which, however, has a collar to the prothorax and the posterior wings 

 a bristle) : wings usually flat in repose; hind wings generally furnished 

 with a bristle ; prothorax covered by a collar or patagium. Very often 

 with ocelli or false eyes on the head behind the antennae. Flight diurnal, 

 crepuscular, most frequently nocturnal. 



WINGS NOT PENNIFORM OR FISSURED. 

 HIND WINGS WITHOUT A BRISTLE AT THE BASE OF THE COSTA. 



* Neuratiou alike in the fore and hind wings. 

 Costal vein long; a basal spur at base; subcostal 4-branched, apical furcate. 

 Wings long, narrow ; discal 3-branched. Median 2-branched. Antennae very short. 



Epialidae. 



** Neuration not alike in lore and hind wings. 

 § Without a costal vein. 

 Subcostal vein bifid ; with disco-central nervule ; median 4-branched. 



Bombycidae (Oylothrix). 



§§ With a costal vein. 

 ■|- With a more or less distinct intercostal cell. 

 Costal vein short; subcostal 3 or 4-branched. 

 Cell nearly circular, more or less distinct; discal branchless ; median 4-branched. 



Bombycidae. 



Costal rather long; subcostal bifid, attenuated. 

 Cell long, narrow: discal fold decided: median 4-branched. F. w. fold thickened. 



Cossidae. 



