APPENDIX. 



ESSAY ON THE SCALES OF THE COLLEMBOLA 

 AND THYSANURA. 



By Joseph Beck. 



The great interest whicli has for many years been 

 taken by micro scopists in tlie scales of this class of 

 insects, and the confusion which has existed as to the 

 particular scale belonging to an individual species, has 

 induced me to avail myself of the kind courtesy of Sir 

 John Lubbock, Bart., to add to his valuable work on 

 the CoLLEMBOLA and Thysanuea a few words in de- 

 scription of the scales of the scale-bearing genera in this 

 group, whilst, at the same time, I gladly embrace the 

 opportunity of performing a tribute of affection to the 

 memory of my late brother, Richard Beck, in super- 

 intending the publication of drawings of the scales of 

 most of the species, executed by his own hand with 

 great care, and admirably transferred upon stone by 

 my relative, A. T. Hollick. 



I enter with some dijfiidence upon a description of 

 the structure of the scales of this class of insects, 

 because I am aware that the attention of many of our 

 most astute observers has been directed to the subject, 

 and yet they have not settled the matter ; I, therefore, 

 can hardly expect to be more fortunate. 



In describing the scale of each species I have given 



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