Evolution and Taxonomy 109 



Zyg^na in the structure of the humeral area of the hind 

 wings. In none of them is costa preserved. The American 

 genera included here are Acoloithus, Triprocris, Pyromorpha, 

 Harrisina, Euchromia, Dahana, Didasys, Lycomorpha, An- 

 atohnis, and Cosmosoma. Of Euchromia I have studied only 

 exotic forms ; Horama and Erruca are unknown to me, but 

 probably belong here also. The position of the Ctenuchidse 

 I have not determined. Superfamily Zyg.Snina. 



CC. THE FRENULUM-LOSERS. 



This division of the order includes those families of Lepi- 

 doptera in which the frenulum has been supplanted by a 

 greatly extended humeral area of the hind wings, (see p. 88). 

 In some of the more generalized forms a rudimentary frenu- 

 lum persists, {Sericaria, Perophora) ; in others it has been re- 

 tained by the male {Drepana). This division includes three 

 groups of families ; the Frenulum-losing Moths, the Skippers 

 (Hesperidse), and the Butterflies. 



D. The Frenulum.- losing Moths. 



E. Moths in which cubitus is apparently three-branched. 



Superfamily Saturniina.* 



* The following expresses my views regarding the affinities of the 

 members of this superfamily : 



A. Moths in which the base of costa of the hind wings is preserved 

 remote from the costal border of the wing. This is shown by the 

 presence of an "intercostal vein" {Sericaria, Fig. 32.) (See p. 78.) 

 Frenulum preserved in a rudimentary state. 



Family BoMBYClD.a=;. 

 AA. Moths lacking an " intercostal vein." (These are the true Saturn- 

 ians. ) 



B. Generalized Saturnians. In these vein V^ retains its primitive 

 position, midway between radius and cubitus ; and there are three 

 anal veins in the hind wings, the distal part of vein VIII being pre- 

 served (Fig. 31.) Frenulum preserved in a rudimentary state. 



Family Perophorid^. 

 BB. More Specialized Saturnians. Vein V, of the hind wings appar- 

 ently a branch of radius (Fig 30) ; anal area of hind wings with not 

 more than two veins, vein VIII having been lost ; frenulum entire- 

 ly superseded by a greatly extended humeral area. 

 C. Antennae of both sexes with only a single pair of pectinations to 

 each segment. ' Family Hemileucid^. 



