EXTERNAL ANATOMY OF INSECTS. 435 



of insects in general. He perceives an analogy between 

 those of this Order and the teeth of quadrupeds ; and 

 therefore divides them into incisive or cutting, laniary 

 or canine, and molary or grinding teeth. He denomi- 

 nates those incisives that are broad, having in some de- 

 gree the shape of a wedge, their external surface being 

 convex, and their internal concave ; whence they are evi- 

 dently formed for cutting. The laniaries are those which 

 have a conical shape, are often very acute, and in gene- 

 ral the longest of any ; and in some insects, as the carni- 

 vorous Orthoptera (and the Libellulina), they cross each 

 other. The molaries are the largest of all, and their 

 purpose is evidently to grind the food. There is never 

 only a single one to each mandible, while the number of 

 the incisives and laniaries is very variable. As the mo- 

 laries act the principal part in mastication, they are 

 nearer the inner base of the mandible or point of sup- 

 port : they serve to grind the food, which has been first 

 divided by the incisives or torn by the laniaries. The 

 carnivorous tribes are destitute of them ; in the omnivo- 

 rous ones they are very small, and in the herbivorous 

 ones they are very large a . So that in some measure 

 you may conjecture the food of the animal from the teeth 

 that arm its mandibles. Of incisive teeth you may find 

 an example in those that arm the end of the mandibles 

 of most grasshoppers (Locusta), and of the leaf-cutter- 

 bees (Megachile Latr.) b ; of the laniary or canine teeth, 

 you will find good examples in the mandibles of the 

 dragon-flies (Libellulina); the two external teeth of the 



a Comparaison des Organes, &c. 7 — • 



b Plate VI. Fig, 6. and XIII. Fig. 5. a'". 



2 F 2 



