INTRODUCTION. 9 



form, as in the genus Anoplognathus, Leach, a construction 

 is to be discovered which may be compared to the keel of a 

 ship, or still better to the sternum of a bird ; and the organ, 

 no doubt, serves for some analogous purpose to all in- 

 sects whose flight in the air or progress in the water 

 Nature intended should be rapid. This keel must be a great 

 advantage to every Coleopterous insect possessing it, and 

 particularly to the bulky Lamellicornes, as materially con- 

 tributing to balance the inconveniences that may arise 

 from the obstruction of their wings by the superincumbent 

 elytra, their greater specific gravity, and the blunt broad 

 surface which they expose to the resistance of the air in 

 flying — inconveniences that insects of the other orders, 

 with the exception of the Orthoptera, are in no degree sub- 

 jected to. The forked base of the pyramid which I have 

 described is supported by strong muscles attached to the 

 sides of the body, and thus appears to serve for another use, 

 namely, the support of the intestine. This organ, which 

 in the Petalocera, Dura, is long and cylindrical, passes 

 close to the back of the insect, directly over the forked 

 base of the prism. But whatever the use of the sternum 

 may be, the above table will sufficiently show that it is 

 not well adapted to be a principle of classification. 



The next organ which demands our attention is the 

 scutellum; not as being in itself of importance, but because 

 Geoffroy's arrangement of the Linnaean genus Scarabteus 

 has been founded on it. It is sufficient to state, in order 

 to prove the absurdity of using this character for great di- 

 visions, that the accurate distinction is not, as has been 

 supposed, whether the scutellum does or does not exist in 

 a lamellicorn insect, but whether it is or is not distinct. 



There are several other parts of an insect which, like 



