314 



With a good deal of probability 1 1 abdominal segments can be 

 counted in instar I of H. hectus. 



For these families I liave colleeted as mucli literature as pos- 

 sible, and I think I ani justified in my conclusion tliat Fracker 

 made a bad choice in raising the prothorax of one of the 

 numerous species to the rank of a fundamental form for his gene- 

 ralized type. 



Sub-order II. Freiiatae. 



As it was Fracker's (1915) iutention to compose an analytic 

 list of determinations of the caterpillars, he had to examine as 

 many diiferent families as possible. In some respects I have 

 started from a different point of view and I had by no means 

 such an extensive ihaterial at my disposal as he had. Though I 

 am convinced that it will be advantageous for a good system of 

 the Lepidoptera to be acquainted with the setal pattern of all 

 the caterpillars, yet I do not believe that the setal pattern in 

 itself is a reliable guide for the limitation of families etc. My 

 own experiences of the Sphingidae^ the Hejnalidae^ the Cossidae, 

 as well as Hofmann's observations of the Pferophoridae etc. 

 have increased my doubts upon that point. This result which 

 later on I intend to discuss more fully, added to my lacking 

 complete series in many families, and on the other hand the nu- 

 merous data given by Dyar, Packard, Fracker and others, al- 

 lowed me to confine my work to certain sclected cases. 



For those families which I have not examined I will confine 

 myself to mentioning the literature I have colleeted, generally 

 without entering into criticism. 



The arrangement of the groups has been made according to 

 Handlirsch's plan (1908), but those families of the so-called 

 Microlepidoptera, which he does not mention, I have entered 

 into the series according to Fracker's system. This is based 

 on a compilation from Walsingham and on published and un- 

 published work of August Busck (1. c. p. 48, 61 sqq.). As this 

 system differs in many instances from that of Handlirsch, I have 



