Structure of Scale of a Species of Mormo. By J. Beck. 811 



one into the other, and adding another link in the chain of evidence 

 in favour of what I have previously maintained, viz. that scales being 

 expansions of the quill, require something to strengthen them, and 

 that for this purpose they are all, whether amongst the Lepidoptera 

 or Thysanura, supphed with ribs running from pedicle to apex, 

 and that the varied appearances seen under the Microscope are due 

 to the irregularities of the membranes of which the ribs form a 

 part.* 



* Since commiinicating the above I have, at the suggestion of the President, 

 examined a large number of the scales of Lepidoptera, and I have invariably found 

 that the corrugations are on one side only, and tliat side the under side, or the one 

 nearest the body of the insect. Great care is required lest a mistake should be 

 made by the moisture running between the scale and the slide, and not on the 

 exposed surface only. 



