398 



convinced that the enemies of the trouts are certainly aecustomed 

 to observe and detect theni. 



The results of my experiments in cultivating Acronyctd psi 

 and Pieris va/n — only to mention two widely differing forms — 

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

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

 afflicted by Ichncitmonids 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 niimerous 

 families: Papilionidae (Griiber, 1884), Nymphalidae (W, Muller, 

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

 (Sharp, 1901) and Sphiugidae (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 Lepidoi^tera we may find these 

 setae, i. a. on Per/cl ista inelanocephakf F. {Tentlu-edinidae). Like 

 the setae of Psi/ura, described by Wachtl and Kornauth, which 

 I found again in Ocucrla and the peculiar elevations of Hetero- 

 canipa (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 bc astonished if it were found that the monosetal 

 tubercula originally havo 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 sccondary setae, often plumose but never long, 

 sometimes borne on chalazae." 



