139 



This case excepted, it seems to me that we can prove that the'fea- 

 ture of plumose setae has been obtained later than that of verrucae. 



If this observation should also be confirmed for other species 

 than those 1 had at my disjwsal or for thoHc of which I was 

 able to collect data from the literature, this mif?ht add to a more 

 aceuratu insight into the phylogeny of the Lepidoittem. 



Scudder's opinion that a homogeneous spreading of the setae 

 over the segment is a primitive ({uality, is decidedly wrong. Na- 

 ked forms and species with a dense covering of setae have always 

 arisen from species with a definite sotal |)attern. (Chapter VI 

 i. a. BombjfjTy Sphinx^ Pieris mtpi). 



The verrucae of some families are reduced again to setae. Now 

 in palaeontology the law of irreversibility holds, which Doli.o (1893) 

 formulates in the following few words: "The development goes 

 on with leaps, is irreversible and limited." 



In discussing the families I have drawn attention to the fact 

 that it can si>metimes be seen from the whole pattern, but often 

 not from the separate setae, whether they have arisen primitively 

 or by reduction of the verrucae. 



In any case therefore for the separate organs we have to do 

 with a reversible development, a fact which deserves our atten- 

 tion in connection with the interest which from the palaeontolo- 

 gical side especially is paid to this problem [compare for instance 

 the exceedingly clever expositions by D^p^ret (1908) and by his 

 critic HoERXES (1911)]. 



The objections which Fracker (1915) makes to my opinion 

 explained above, do not appear to me to be quite convincing. 

 For particulars I refer to the Xoctuidae, Chapter VI. 



Concerning the separate series of development I can sum up 

 my results in the following way (Chapter VI): 



The Hepialidae differ rather from the FRENATAE, but at the 

 same time present such important differences from the other 

 JUGATAE and even amongst themselves, that it is impossible to 

 fix a definite, strictly circumscribed pattern for this sub-order. 

 Verrucae occur on the Eriocephalidae. 



