OF THE SKELETON. 143 



sion which prevails in anatomical nomenclature, there is 

 no entomologist of moderate information but would at 

 once understand the nomenclature here employed, for 

 other names have seldom been adopted by any one but 

 their inventor, and thus have never obtained the sanction 

 of usage. The possession of one mouth, two eyes, four 

 wings, and six legs, will at all times distinguish an animal 

 as being properly and strictly an insect ; and the segments 

 on which these parts are respectively situated are invari- 

 ably the same. The possession of a greater or lesser 

 number of antennae, mouths, wings or legs, would at once 

 indicate that an animal belonged to some other division, 

 except in a few instances where wings are wanting, as in 

 some species of Phasma, and the connexion of these with 

 insects is clearly proved by the occurrence of numerous 

 closely allied species which invariably possess wings. It 

 may not be amiss here to repeat that insects form a portion 

 of a larger group of animals, to all of which the external 

 skeleton is a character in common. 



The fifth segment is the propodeon ; it is generally of 

 less size than either of the three preceding segments, and 

 is frequently so closely united to the metathorax as to be 

 distinguished from it only by a sutural line. The propo- 

 deon and following segments never bear limbs of any 

 kind, whether wings or legs. Here it must be observed 

 that the 2nd, 3rd, 4th, and 5th segments, are so closely 

 united in Hymenopterous insects, that it is a matter of 

 some difficulty to trace their divisions. In the locust, 

 which is acknowledged by all entomologists to belong 

 to the same class as the Phasma and Mantis, the third 

 and fourth segments, instead of being distinct and sepa- 

 rate as in those insects, are become as it were mixed, 

 and their limits undefined, and were we unassisted by 

 the presence of wings and legs, it would be next to 



