242 THE MICROSCOPE AND ITS REVELATIONS. 



a row of curved booklets on the anterior margin of the posterior wing, 

 which lay hold of the thickened and doubled-down posterior edge of the 

 anterior wing. These booklets are sufficiently apparent in the wings of 

 the common Bee, when examined with even alow magnifying power; bat 

 they are seen better in the Wasp, and better still in the Hornet. The 

 peculiar scaly covering of the wings of the Lepidoptera has already been 

 noticed ( 619); but it may here be added that the entire wings of many 

 of the smaller and commoner insects of this order, such as the Tineidce 

 or ' clothes-moths,' form, very beautiful opaque objects for low powers; 

 the most beautiful of all being the divided wings of the Fissipe tines or 

 ' plumed moths/ especially those of the genus Pterophorus. 



639. There are many Insects, however, in which the Wings are more 

 or less consolidated by the interposition of a layer of horny substance 

 between the two layers of membrane. This plan of structure is most 

 fully carried-out in the Coleoptera (Beetles), whose anterior wings are 

 metamorphosed into elytra or ' wing-cases-/ and it is upon these that the 

 brilliant hues by which the integument of many of these insects is dis- 

 tinguished are most strikingly displayed. In the anterior wings of the 

 ForficulidcB or Ear wig- tribe (which form the connecting link between 

 this order and the Orthoptera), the cellular structure may often be readily 

 distinguished when they are viewed by transmitted light, especially after 

 having been mounted in Canada balsam. The anterior wings of the 

 Orthoptera (Grasshoppers, Crickets, etc.), although not by any means so 

 solidified as those of Coleoptera, contain a good deal of horny matter; 

 they are usually rendered sufficiently transparent, however, by Canada 

 balsam, to be viewed with transmitted light; and many of them are so 

 colored as to be very showy objects (as are also the posterior fan-like 

 wings) for the Electric or Gas-microscope, although their large size, and 

 the absence of any minute structure, prevent them from affording much 

 interest to the ordinary Microscopist. We must not omit mention, how- 

 ever, the curious Sound-producing apparatus which is possessed by most 

 insects of this order, and especially by the common House-cricket. This 

 consists of the ( tympanum ' or drum, which is a space on each of the 

 upper wings, scarcely crossed by veins, but bounded externally by a large 

 dark vein provided with three or four longitudinal ridges; and of the 

 ' file ' or ' bow/ which is a transverse horny ridge in front of the tym- 

 panum, furnished with numerous teeth: and it is believed that the sound 

 is produced by the rubbing of the two bows across each other, while its 

 intensity is increased by the sound-board action of the tympanum. The 

 wings of the Fulgoridm (Lantern-flies) have much the same texture with 

 those of Orthoptera, and possess about the same value as Microscopic 

 objects; differing considerably from the purely membranous wings of the 

 Cicadse and Aphides, which are associated with them in the order Homop- 

 tera. In the order Hemiptera, to which belong various kinds of land 

 and water Insects that have a suctorial mouth resembling that of the 

 common bug, the wings of the anterior pair are usually of parch men ty 

 consistence, though membranous near their tips, and are often so richly 

 colored as to become very beautiful objects, when mounted in Balsam 

 and viewed by transmitted light; this is the case especially with the ter- 

 restrial vegetable-feeding kinds, such as the Pentatoma and its allies, 

 some of the tropical forms of which rival the most brilliant of the Beetles. 

 The British species are by no means so interesting; and the aquatic kinds, 

 which, next to the bed-bugs, are the most common, always have a dull 

 brown or almost black hue: even among these last, however, of which 



