THE CANADIAN ENTOMOLOGIST. 



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that I was correct in my observation. Mr. Dyar kindly writes me upon 

 the specimens as follows : " They are evidently true Saturn ians, as you 

 wrote them to be, but differ from any which I have seen before, in lacking 

 the unpaired dorsal tubercle on eighth abdominal segment. The tubercle 

 is absent also in Anisota {Citheroniidce), but in no other genus which I 

 have yet seen. I thought at first that the unpaired tubercle was simply 

 absent in Anisota, and wrote my first article on larvae under that impres- 

 sion. But when I had the opportunity of studying the larvse in stage I., 

 I found that really the original tubercle i. remained unconsolidated, and 

 ii. disappeared, just as on the more anterior segments. But in these 

 Saturnians {pavoiiia tnajor and minor) we cannot say whether i. is consoli- 

 dated into an unpaired tubercle with its fellow and the structure lost, or 

 whether i. is separate and ii. is gone. The first stage would probably not 

 help us here, as the primitive first stage is lacking in all the Saturnians 

 which I have seen. But, by analogy with Anisota, I conclude that i. is 

 unconsolidated. S. pavonia minor is the more generalized form, when 

 we come to consider the mature larva. S. pavonia major has suffered a 

 modification in the evolution, and is more specialized. The secondary 

 hairs are greatly reduced, but those that are left, together with the central 

 sette on the tubercles, are elongated and have acquired flattened and 

 enlarged tips ; the tubercles themselves stand up prominently and are 

 coloured blue, strongly suggesting a simple form of our Satnia type. 

 I seem to see even a trace of the predominance of the subdorsal tubercles 

 on meso- and metathoracic segments, which is so marked in the American 

 forms. As to colour, the primitive black, seen in generalized larvse like 

 our Hemileucids, Pseudo/iazis, etc., is replaced gradually during ontogeny 

 by green, as is done in Samia, etc., and in atheroma. A beautiful 

 adaptation to the environment." 



Thus it appears from Mr. Dyar's study, that our Samia cecropia and 

 allies are descendants of the same stock with the European Saturnia, 

 while the position I have assigned to Satnia as next to Saturnia is 

 justified. There remains for me to point out some facts with regard to 

 the formation of the cocoon in our American genera which induces my 

 arrangement of the family. In Attacus, Philosamia and Callosamia, the 

 larva attaches the deciduous leaf, which forms the basis and natural 

 attachment for its web, firmly to the branchlet by a pedicel of silk. 

 Evidently this is an acquired habit. It has been found more useful to 

 the species that the cocoon be prevented from falling to the ground with 



