Evolution and Taxonomy iii 



DDD. The Butterflies. — If we remove the Hesperidae from 

 this division of the order as indicated above, the butterflies 

 form a well defined group. It contains, however, two distinct 

 lines of descent which separated very early in the history of 

 the group. In one, after the abortion of the base of media, 

 vein V.2 migrated towards cubitus, forming a four- branched 

 cubitus ; in the other, this vein migrated in the opposite di- 

 rection. There was also a difference in the order of the re- 

 duction of the anal areas of the two pairs of wings. See 

 page 44 for a discussion of the importance of this character. 



E. Butterflies in which cubitus is apparently four-branched; 

 and in which the anal area of the hind wings is more reduced 

 than the anal area of the fore wings. In the fore wings all 

 three of the anal veins are at least partially preserved, while 

 in the hind wings there is only a single anal vein. PI. II, 

 Fig. 2. Family Papiuonid^. 



EE. Butterflies in which cubitus is apparently three- 

 branched ; and in which the anal area of the fore wings is 



I infer from the figure and description oi Lacosoma that it also belongs 

 here. Perophora has been classed in the Psychidae merely because its 

 larva is a case-bearer. But it presents no affinities to the Psychidse be- 

 yond belonging to the same suborder, even in larval habits. The case 

 of the larva oi Perophora is of an entirely different type from that char- 

 acteristic of the Psychidae. 



HemilEUCId^. — This family represents a distinct line of develop- 

 ment within the Saturniina, which separated from the branch giving 

 rise to the Ceratocampidje and Saturniidse before the origin of the pecu- 

 liar form of antennae characteristic of these families. For although the 

 Hemileucidse lack this peculiar specialization, the extent of the migra- 

 tion of vein V^ that has taken place in this family, indicates a higher 

 degree of specialization in another direction than exists in any of the 

 Ceratocampidae or in the lower genera {Coloradia and Hyperchiria) of 

 the Saturniidae. This family is represented in this country by two gen- 

 era, Heniileuca and Pseudohazis. 



Ceratocampid^.— I have nothing to add to the well known charac- 

 teristics of this family. There are five North American genera : athe- 

 roma, Eades, Sphingicainpa, Afiisota, and Dryocampa. 



SaturniiD/S;. — We have eight genera representing this family ; these 

 are, beginning with the most generalized : Cotoradia, Hyperchiria 

 Calosaturnia, Telia, Actias, Saturnia, Attacus, and Samia. 



