660 MODE OF DISPLAYING TEGUMENTARY APPENDAGES. 



515. In examining the Integument of Insects, and its Appen- 

 dages, parts of the surface may be viewed either by reflected or 

 transmitted light, according to their degree of transparence and 

 the nature of their covering. The Beetle and the Butterfly tribes 

 furnish the greater number of the objects suitable to be viewed 

 as opaque objects ; and nothing is easier than to mount portions 

 of the Elytra of the former (which are usually the most showy 

 portions of their bodies), or of the Wings of the latter, in the 

 manner described in § 155. The tribe of Curculionidce, in which 

 the surface of the body is beset with Scales having the most 

 varied and lustrous hues, is distinguished among Coleoptera for 

 the brilliancy of the objects it affords ; the most remarkable 

 in this respect being the well-known Curculio imperialism or 

 ' Diamond Beetle ' of South America, parts of whose Elytra, when 

 properly illuminated and looked-at with a low power, show like 

 clusters of jewels flashing against a dark velvet ground. In 

 many of the British Curculionidse, which are smaller and far less 

 brilliant, the Scales lie at the bottom of little depressions of the 

 surface ; and if the Elytra of the Diamond Beetle be carefully 

 examined, it will be found that each of the clusters of Scales which 

 are arranged upon it in rows, seems to rise out of a deep pit which 

 sinks-in by its side. The transition from Scales to Hairs is ex- 

 tremely well seen by comparing the different parts of the surface 

 of the ' Diamond Beetle ' with each other. The beauty and bril- 

 liancy of many objects of this kind are increased by mounting 

 them in cells in Canada balsam, even though they are to be viewed 

 with reflected light ; other objects, however, are rendered less at- 

 tractive by this treatment ; and in order to ascertain whether it is 

 likely to improve or to deteriorate the specimen, it is a good plan 

 first to test some other portion of the body having Scales of the 

 same kind, by touching it with Turpentine, and then to mount the 

 part selected as an object, either in Balsam, or dry, according as 

 the Turpentine increases or diminishes the brilliancy of the Scales 

 on the spot to which it was applied. Portions of the Wings of 

 Lepidoptera are best mounted as opaque objects, without any other 

 preparation than gumming them flat down to the disk of the 

 Wooden Slide (§ 155) ; care being taken to avoid disturbing the 

 arrangement of the scales, and to keep the objects, when mounted, 

 as secluded as possible from dust. In selecting such portions, it is 

 well to choose those which have the brightest and the most con- 

 trasted colours, Foreign butterflies being in this respect usually 

 preferable to British ; and before attaching them to their Slides, 

 care should be taken to ascertain in what position, with the 

 arrangement of light ordinarily used, they are seen to the best 



whilst the scales will adhere closely to the glass. As by this method, 

 however, the Insects will frequently hop away and escape, they may be 

 made perfectly motionless by applying, with a camel's hair pencil, a 

 little Chloroform near them, upon the paper, before the cover is moved." 



