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On the Structure of Butterfly and Moth Scales. 



By T. F. Smith. 

 {Read November 25th, 1887.) 



At the last ordinary meeting of this Club I read a paper on the 

 structure of butterfly and moth scales, and exhibited some speci- 

 mens showing the villi discovered by Dr. Koyston-Pigott. There 

 was no doubt in my own mind about the villi, nor, I think, in the 

 minds of any of those who saw them ; but the specimens had been 

 far too short a time in my possession to allow me to speak posi- 

 tively of their position, although I expressed an opinion that, in one 

 instance at least, they were between the two membranes of the 

 scale. 



Since then, however, I have been able to examine torn specimens, 

 and have now no hesitation in asserting that this is the structure 

 in all cases. If you come to think about it you will see that it is 

 almost impossible it should be otherwise, seeing that these little 

 filaments are often not more than the 100,000th of an inch in 

 diameter, and could not stand the wear and tear during the insect's 

 life, unless protected in some such manner. 



Of course, if there were positive evidence that the villi were out- 

 side the membranes there would be an end of all speculation at once, 

 but to me all the evidence so far points one way, and that in an 

 opposite direction. In no single instance have I seen them project 

 beyond the outline of the scale even when twisted on itself, and it 

 would be impossible but what some would project so if outside. 

 But what I chiefly rely upon is the evidence of torn scales, such as 

 the specimen I have brought here to-night for your inspection, and 

 which will, I think, convince you that the villi are inside and not 

 out. 



The scale under the microscope is from Urania rhypheus, and it 

 happens to be a scale of Urania in which the villi were figured, as 

 pseudo-beading, by Mr. Mclntire, about a dozen years ago in the 

 " Monthly Microscopical Journal." The villi on this scale differ 

 from many in not being so numerous, but appear in well-defined 



Journ. Q. M. C, Series II., No. 21. 16 



