138 



convinced that the enemies of the trouts are certainly accustomed 

 to observe and detect them. 



The results of my experiments in cultivating Acrowjcta pst 

 and Fieris napi — only to mention two widely differing forms — 

 brought me to the same conclusion as W. Muller came to, after 

 an experience of many years viz: that naked forms are as much 

 afflicted by Ichneumonids as the species which bear large spines. 



In the first instar many setae are so-called glandular hairs. 



The systematic signification of these generally bifurcated setae 

 cannot possibly be very great in my opinion. They occur in numerous 

 families: Papilionidae (Gruber, 1884), Nymphalidae (W. Muller, 

 1886), Notodontidae and Pterophondae (Packard, 1890), Piendae 

 (Sharp, 1901) and Sphingidae (Packard, 1905). For this last 

 family I have given an accurate description of the form and it 

 was only later on that I studied Packard's drawing which dif- 

 fers in some respects from mine. 



Also outside the order of the Lepidoptera we may find these 

 setae, i. a. on Pen'clista melanocephala F. (Tenth redinidae). Like 

 the setae of Psilura, described by Wachtl and Kornauth, which 

 I found again in Ocneria and the peculiar elevations of Hetew- 

 campa (Packard, 1895), I consider them to be rudimentary or- 

 gans which are disappearing and which now do not possess any 

 important function for the welfare of their bearers. 



I should not be astonished if it were found that the monosetal 

 tubercula originally have been tactile organs. 



In numerous families the monosetal tubercula developed into 

 warts (verrucae), without it being possible to attribute any sy- 

 stematical importance to this feature. 



In my opinion more importance should be attached to the setae 

 being plumose or not. As far as I know plumed setae only occur 

 on those caterpillars which possess verrucae, but not even on all 

 of them. The only exception known to me is the family of the 

 Hesperidae of which Fracker says on p. 127 "The head is cove- 

 red with numerous secondary setae, often plumose but never long, 

 sometimes borne on chalazae." 



