560 EXTERNAL ANATOMY OF INSECTS. 



in this Order is best exemplified in the common water- 

 beetle (Dj/tiscus marginalis). This at the inner base 

 of the elytra has a membranous fringed alula resembling 

 those of Diptera ; to the lower fold of this the extremity 

 of the frcenum is attached, which forms a right angle with 

 the scutellum, and the upper fold is attached to the base 

 of the elytrum a . The object of this appendage is pro- 

 bably to prevent the dislocation of these organs, which 

 seems to indicate that they are used more in flight than 

 those of other beetles. The Blattce also, in the next Or- 

 der, have a winglet attached to the anal area of the teg- 

 mina. The frcenum, as in the preceding Order, lies un- 

 der the margin of the scutellum and dorsolum, but which 

 here forms one uninterrupted transverse line ; it is near- 

 ly vertical, and is attached to the alula. The structure 

 is not very different in the other Qrtlioptera b , but the 

 frcenum is surmounted or strengthened by one or two 

 ridges ; in Mantis it runs from the scutellum in an an- 

 gular or zigzag direction — but in all it is attached im- 

 mediately to the tegmen. In the Heteropterous Hemi- 

 ptera it is represented by the narrow bead adjacent to the 

 scutellum on each side c , which dilates into a flat plate as 

 it approaches the Hemelytrum, with the Anal Area of which 

 it is connected. But the Homopterous section of the Order 

 in question furnishes examples of the most remarkable 

 structure of this countercheck, which proves that it is real- 

 ly, what its name imports, a bridle. If you examine the 

 great lanthorn-fly (Fulgora latemaria), or any species of 

 Tettigonia, &c, you will find adjacent to the scutellum 



a Plate XXIII. Fir.. 6. e". b p LATE yill Fig. 12. V . 



£ Ibid. Fig. 20. I. 



