Scales of Insects and Fish. 43 



minuteness. The degree of distinctness with which 

 these markings can be shown with various magnifying 

 powers forms a useful test of the excellence of the 

 microscope employed, and scales mounted for this 

 special purpose are supplied by opticians as " test- 

 objects." 



So much for the scales of moths and butterflies. 

 Some other insects, including several beetles, are also 

 ornamented with scales. In fact, whenever I see an 

 insect presenting the peculiarly powdery soft appear- 

 ance of a moth or butterfly's wing, I always guess 

 it has scales, and generally find my supposition 

 correct. The Weevils (Curculionidce is the learned 

 name) are a tribe of beetles in which these scales may 

 be well observed. One of them is represented at 

 Plate IV., fig. 1. It is a dingy slow-moving little 

 beetle ; but how differently we regard it after we have 

 once seen it in the microscope ! When magnified 

 slightly we see that it is covered, or rather sprinkled 

 over with beautiful little roundish scales, arranged 

 with considerable regularity. These scales, when 

 magnified 100 diameters, gleam each like a scallop- 

 shell of burnished gold, and placed on the dark wing- 

 case of the beetle, are truly splendid (fig. 2). 



There is another Curculio, somewhat similar in 

 shape to this one, but smaller and more promising in 

 appearance, as it is of a silvery green colour. It is 

 very common in April and May ; I have seen hun- 

 dreds on large beech-trees. Its body is really Hack, 

 with green scales of surpassing brilliancy. Fig. 3 

 gives an idea of their shape and arrangement, but no 



