i;i5 

 CHAPTER VIII. 



QeMEKAL considerations and synopsis of the RE8ULTS. 



In the preceding pages I have tried to lay duwn a general 

 fuundation for the armature of caterpillars. 



In consequence of the shifting of the stigniuta over niesothorax 

 and metathorax and the development of the wingH on them, T 

 take it for granted, that these segments are to be considered us 

 being secondarily moditied. 



On account of the anatomical differences with the abdomen, 

 this result might a priori be expected, and the chaetotaxy on 

 these s(>gment8 j)rovide8 proofs that the setal pattern also has 

 undergone secondary modifications. The prothorax too has taken 

 part in these changes by obtaining the stigma which originally 

 was placed on the niesothorax. Hence it is not desirable to start 

 from th(>se segments in reconstructing the primitive ])attern, as 

 Tsou and Fkackek have done (Chapters III and V). 



The anal segments too differ in structure and even vary in 

 number. This probably happens in connection with a process of 

 reduction which in some species has farther advanced than in 

 others (Chapter IV). 



Among the remaining eight or nine abdominal segments a few 

 occur bearing legs and others without them. On account of embryo- 

 logical facts as well as of the presence of the setae pedales, I 

 think it allowable to consider the segments with legs as the 

 more primitive ones (Chapter IV). 



From the literature, Chapter II, it appears that all the different 

 investigators of the setal pattern have introduced a nomenclature 

 of their own, in which many made use of numbers. As some of 

 them indicated totally different setae by the same number and 

 as the same setae are indicated by different investigators by widely 

 different numbers, a great confusion has arisen, as is best illus- 

 trated by Plate I, fig. 1—21. 



I have therefore been led to use a nomenclature which agrees with 

 that of Weismann, W. Muller, Scudder and J. F. van Bemmelex. 



