301 



the thoracic segments in general and the prothoracic one in par- 

 ticular, to bear a primary character. I think I have shown suflfi- 

 ciently in chapter III that this a-priori view does not deserve 

 general acceptance. 



In criticizing the different sy sterns and especially that of Fracker, 

 I have liad the opportunity of exphiining my opinion on the 

 nonienclature. 



Therefore it will not cause surprise that I begin by first 

 taking the abdominal pattern and that, as neither the use 

 of numbers nor of Fracker's Greek letters appeared possible, I 

 have come back to the use of names which at the same time 

 express the place of the seta on the segment. In composing my 

 nonienclature I have tried to keep in agreement as far as possible 

 with the following writers : 



Weismann (1876), Muller (1886), Scudder (1889), Schröder 

 (1894), QuAiL (1900), J. F. van Bemmelen (1912). 



In accordance with Dyar and Fracker I think that in the 

 composition of a primitive pattern a verruca (wart), a scoliis (spine), 

 a tuberadwn (elevation which mostly bears one or more setae) and 

 a seta ought to be considered homologous with each other. 



I should like to add to this series of homologous organs a 

 pirjinental spot. I think that the seta is the original part, and 

 that the other organs are its secondary modifications. A homo- 

 geneous spreading of the setae, as also their complete absence, 

 must be considered as secondary features. 



The reduced patterns of the anal segments have also arisen in 

 a secondary way, though they often lead to pseudo-primitive 

 conditions. 



In discussing the results I intend to refer again to these facts 

 (chapter IX). 



To be able to shorten the descriptions I have also given cyphers 

 to the patterns as a whole: Type I, Ia etc. The deviations from 

 this pattern can be easily indicated so that with a few words the 

 place of all the setae can be exactly mentioned. In connection with 

 my remarks in Chapter IV it should be pointed out, that the anal 



