331 



1. The ooalescenoe of v. sitpmsfif/iiK/lis with r. postsf/j/iiialis. 



2. The disapiiearancc of v. dorsalls in different ways. 



3. Tlie structure of the setae becoming more intricate in the 

 course of the successive moultings. 



4. The presence of peouliar setae on Lijinantria dispar. 



5. The disappearance of the prothoracic shield. 



6. The presence of verrucae on the pnpa, to which Swammerdam 

 (1737) already drew attention. 



7. The verrucae on the larva are arranged according to type I 

 or to type \h. 



Family Liparidde Linn. Plate XI, fig. 8 — 11. 

 Lymantria (Ocner'ia) dispar L. 

 Ma te ri al in alcohol and living animals (summer 1915). In the 

 successive instars of caterpillars the same pattern is always found, 

 the tubercles are warts with many setae. 



Instar I. Duration 12 days. Length 4 mm. The setae are diffe- 

 rent in form viz. : 



1. Very short feathered, light coloured ones, with a length of 

 + 1 '/2 — 2 mm. (the side-branches are + 7 ,a). The base is 

 enclosed in the black case of the wart. 



2. Not feathered ones, mostly 400 — -500 [j.. long and coloured deep 

 brown (PI. XI, fig. 10). The lower part is ± 100 /y. long and a little 

 narrower than the elevation of the wart on which the seta stands. 

 A little bladder follows, with almost colourless wall. The diameter 

 is + 20 y,. Through the presence of this bladder movements of 

 the top part of the seta are rendered possible. This part is 

 + 300 [j. long and tapers into a point. At first I thought that 

 these peculiar setae were of use during hatching, as I imagined 

 that before and during the removal of the skin, they were folded 

 up. The examination of newly hatched larvae showed me, however, 

 that there these setae already stand upright. The number of the 

 bends is decidedly not larger than afterwards. I surmise that the 

 same organs occur in the closely related Lijmmitria monacha. 

 According to Sharp (II, p. 407), AVaciitl and Kornauth (1893) 



