[ 107] 



Zbc IDilli all^ BcaMno iDi6C0VClv^ on Butter** 

 tl^ anb ni^oth Scales. 



By Dr. Royston-Pigott, M.A., F.R.S. 

 Plate XIV. 



^T OW that glasses of great power can be cheaply obtained, a 

 ^ completely new field of enjoyment is to be found in the 

 examination of the Villi and beading of these scales, 

 mounted dry. 



In 1 88 1, a short notice on A^illi was published by the Royal 

 Society. Since that time, the writer, having mounted about 450 

 species and spent most of his leisure in their investigation, has the 

 pleasure of announcing about 1 2 varieties of these Villi at present. 



In 1880 they were with much difficulty descried on the scales 

 of the /ic'd Admiral ; but recently much larger and prominent 

 Villi have fortunately been discovered. They may be classed as 

 internal^ lyhig between the two membranes forming a scale ; 

 external, sometimes penetrating the inner membrane from within, 

 attached to the ribs and peeping outwards in an extraordinary 

 variety of forms, generally tipped with brilliant heads ; superficial, 

 being distributed in most grotesque forms upon the surface of 

 the scales next the wings. 



Some further description of scales is here required. They are 

 all ribbed on the outer or air surface and, excepting the Villi, 

 smooth where they rest upon adjacent scales. Another point 

 should not be omitted. They are all saturated with a peculiar 

 scale-oil, which may by pressure be made to play a prominent part 

 by developing structure as it flows to and fro within the sac. It 

 has a very strong preservative power, and refuses for an immense 

 time to evaporate.- 



These little wonders are best seen when a small portion of the 

 scale adheres to the cover-glass and when the ribbing lies below. 



A very exact vertically-measuring apparatus records some of the 

 Villi erected, i — 5000th of an inch, but generally they are only 

 from I — 1 0,000th to I — 8oooth aloft above the unribbed mem- 

 brane which lies compactly upon the wing. 



* I have some I'odura scales, 60 years old, quite full of this oil still. 



