18 



development (as a classical example I cite the Sphingid with a 

 complete setal pattern, mentioned by Weismann), there it is 

 absolutely certain that a classification like this must prove to be 

 inefficient as soon as a great number of different forms of one 

 family are compared with each other. Fracker who in 1915 once 

 more tried to compose an analytical list for the determination 

 of caterpillars, has been obliged to use other characteristics, such 

 as the rows of crochets on the abdominal legs. At the same time 

 Fracker very logically begins with the most generalized families 

 and gradually passes to the most specialized ones (1. c. p. 49 — 59). 

 Fracker's main classification is no longer based on the setae but 

 on other characteristics. He introduces a completely new nomen- 

 clature, against which I intend to raise my objections in a following 

 chapter. It is a great pity that, where he apparently had extensive 

 material at his disposal, he paid so little attention to the onto- 

 genetic changes of the setal pattern. During the discussion of 

 the different families I shall have to point out some mistakes 

 in Fracker's work (see e. g. Piendae^ Bomhyx inori, Porthesia 

 chrijsorrhoea etc.). 



Tsou who worked at about the same time as Fracker, published 

 a method in 1914 for determining the length and the breadth 

 of a seta on the segment. He examined almost exclusively a full- 

 grown Cossus cossuSj Hepialus humuli and Jaspedia celsia. He 

 chooses the prothorax as point of issue for his deductions, on the 

 not quite scientific ground that it is the first segment of the body. 

 (1. c. p. 228). He also groups the setae in a peculiar way of 

 which he himself admits that it is more or less artificial. I cannot 

 but agree with him in this qualification. As I do not agree with his 

 method of comparing fullgrown caterpillars of different families 

 with each other without attending to the first instars at all, nor 

 with his taking the prothorax as the starting-point, nor with his 

 uniting the setae to arbitrary groups, I think that here it is 

 sufficient simply to mention his work. 



0. HoFMANN in 1898 devoted a study to the caterpillars of the 

 Pterophoridae. Dyar had brought forward the great systematic 



i 



