158 PHOTO-MICROGRAPHS. 
both because of their varied and curious shapes, 
and on account of the brilliant colors which some 
of them exhibit. They may be compared with 
the epithelium cells covering the surface of ani. 
mals, and also with the feathers of birds. Like 
the latter, they not only protect the surface cov- 
ered by them, but they contain the pigments used 
so lavishly by nature in the decoration of the in- 
sects of this family. The metallic lustre and iri- 
descence exhibited by many of these scales is, 
however, due to their structure, and not to the 
presence of pigment. 
The scales are arranged upon the wings and 
bodies of these insects in imbricated rows, in which 
they overlie each other like the shingles upon 
the roof of a house. Each scale is held in place 
by a projection at the inner and acute extremity, 
which is inserted into a socket provided for its 
reception upon the surface of the body or wing. 
Much attention has been given by microscopists 
to the study of these scales, with reference to their 
structure and the nature of the minute markings 
which are found upon many of them. For informa- 
tion upon this subject, the reader is referred to the 
work of Dr. Carpenter.’ 
1 «The Microscope and its Revelations,”’ 6th edition, pp. 723-733. 
