88 PREPARATION AND MOUNTING 
from them. As they are, however, most frequently mounted 
in balsam or liquid, they will be more fully noticed in other 
places. 
The scales of fishes are generally mounted dry when 
used as ordinary objects; but for polarized light, balsam or 
liquid must be used, as noticed in Chapter IV. To mount 
a fish-scale, however, in a satisfactory manier, care must be 
taken that it is perfectly clean. ‘This can be accomplished 
only by careful washing, in which process soft camel-hair 
pencils will often be useful. When the slime or mucus has 
once dried, it is very difficult to remove. The variety and 
beauty of these are quite surprising to the novice. It is 
also very interesting to procure the skin of the fish when 
possible, and mount it on a separate slide to show how the 
scales are arranged. The sole is one of the most unusual 
forms, the projecting end of each scale being covered with 
spines, which radiate from a common centre, while those at 
the extremity are carried out somewhat resembling the rays 
of a star. One of the skates has a snine projecting from the 
centre of each scale, which is a very curious opaque object, 
especially when the skin is mounted in the manner described. 
The perch, roach, minnow, and others of the common fishes 
give the student good objects for his cabinet, and may be 
procured without difficulty. The scale of the turbot is a 
splendid object for the polariscope when mounted in balsam. 
Insects which are very transparent, or have the “ metallic 
lustre” with which any medium would interfere, are mounted 
dry. ‘The diamond-beetle, before mentioned, is a splendid 
example of this; the back is generally used, but the legs, 
showing the curious feet, are very interesting objects. In-. 
deed, amongst the legs and feet of insects there is a wide 
field of interest. When they are of a horny nature, it is 
best to dry them in any form preferred, but to use no 
pressare; when, however, they. are wanted flat, so as to 
show the feet, &c., extended, they must be dried with a 
gentle pressure betwixt blotting-paper if possible. But this 
will be treated more fully in Chapter IV. 
