26 
In my opinion the setae must be homologized according to their 
arrangement in regard not only to each other, but also to other 
organs occurring on the external surface of the larval body, of which 
the stigma undoubtedly is the most important. Yet the place of this 
opening is not always the same. For on the prothorax it is situated 
near to its caudal border, the segments of the abdomen on the con- 
trary bear their stigmata in their oral half. A dislocation of the 
stigma therefore probably has taken place. Without deciding which 
position of the stigma should be considered the most primitive *), 
one thing may be safely accepted. as an incontestable fact, i.e. 
that such a dislocation will exercise a certain influence on the setae 
in its neighbourhood. 
FracKeR however, judging by his fig. 1 (9 and #), seems to suppose 
that the stigma might be able to dive, as it were, beneath a seta and 
so pass it without in the least disturbing its position. I am sorry 
to say that L cannot possibly agree with such an opinion, as I am 
convinced that a seta on the oral side of the stigma will always 
maintain its anterior position. For this reason I prefer for the 
setae a system of names instead of ciphers or letters, because in 
that way the situation of the setae is indicated at the same time. 
Moreover by adopting names, I can remain in harmony with the 
nomenclature of Wertsmann, W. Mürrer and J. F. van BEMMELEN, 
and so act according to the rules of priority, which should be 
observed also in cases like these. For the sake of clearness the use 
of names is by far to be preferred to that of cipbers or letters. 
My observations led me to the conclusion that a far going corre- 
spondence exists between the arrangements of the setae (hairs), tubercles 
(eminences usually bearing one or more setae), verrucae (warts with 
many setae), sco/i (prominent spines), and pigmental spots. 1 therefore 
consider all these dermal products to be homologous. A homoge- 
neous dispersion of setae or their total absence are both secondary 
modifications. 
Different types of pattern may be distinguished, but they can be 
deduced from each other. 
Type I. The most widely spread, as it occurs on the abdominal 
segments of almost all caterpillars, when newly hatched (Instar J), 
and in many, species is retained during the whole larval period. 
Moreover, the pattern on the prothorax of these caterpillars corre- 
sponds in its main features with the abdominal one. In the following 
list the setae marked with an asterisk usually occur on the prothorax 
1) In a following paper I hope to give some information in this question, 
