15 



from them, are hypertrophied piliferous warts, the warts with the 

 seta or hair which they bear being common to all caterpillars. 



2. The hypertrophy was probably primarily due to a change 

 of station from herbs to trees, involving better air, a more equable 

 temperature, perhaps a different and better food. 



3. The enlarged and specialized tubercles developed more rapidly 

 on certain segments than on others, especially the more prominent 

 segments, because the nutritive fluids would tend to more freely 

 supply parts most exposed to external stimuli. 



4. The stimuli were in great part due to the visits of insects and 

 birds, resulting in a mimicry of the spines and projections on the 

 trees, the colors (lines and spots) were due to light or shade, with 

 the general result of protective mimicry or adaptation of tree-life. 



5. 6, 7, 8 and 9. Through heredity these first steps in the 

 evolution, in the beginning due to primary factors of evolution 

 (Xeo-lamarckism) became constant, due to segregation and natural 

 selection, bi'oause intercrossing with low feeders would cease. 



As the probable time of the origin of the large setae and warts 

 Packard mentions : „the critical time attending or following the 

 close of the Palaeozoic or the early part of the Mesozoic age, 

 the time when deciduous trees and flowers probably began to 

 appear" (1. c. p. 506). 



In 1893 Packard refers again to this subject, in which he 

 thinks he has found a basis for a natural classification of the 

 Bombyces (see chapter VI). 



Dyar independently of W. MCller, examined the primitive 

 pattern in 1894 and has even made an analytical list for deter- 

 minations according to the setae. 



As for the nomenclature I refer to Chapter V. His table 

 follows here. 



Synopsis of the Families of Lepidopterous Larvae. 

 A. More than one tubercle on the third annulet and more than 

 three on the base of the leg. — Jugatae, Hepialidae. 

 A A. Not more than one tubercle on third annulet and only six 

 above the base of the leg. — Frenatae. 



