EXTERNAL ANATOMY OF INSECTS. 547 



of the notch and calcar a , they are prehensory legs ; in 

 Scarites belonging to that tribe, the Lamellicorn beetles, 

 and the mole- cricket, they are fossorious legs, or proper 

 for digging b ; in Mantis, Nepa, and some Diptera, they 

 are raptorious, or fitted to seize and dispatch their prey c : 

 they are used also by many insects to clean their head, 

 eyes, and antennae, &c. For many of these purposes 

 they cannot be fit without: a structure different from that 

 of the other legs, which renders it a matter of as great 

 convenience in descriptions to speak of them and their 

 parts under different names from those of the legs, as it 

 is of the arms of man ; on this account it is that I propose 

 to give to the fore-leg and its part the names by which 

 the analogous parts, or what are so esteemed, in the hu- 

 man species are distinguished; — when spoken of in com- 

 mon with the other legs, they may still be called the fore- 

 legs. 



* * Alitruncus. The alitrunk is the posterior segment 

 of the trunk, which below bears the four true legs, and 

 above the organs for flight or their representatives. In 

 treating of this part we may consider its insertion or ar- 

 ticulation, its shape, composition, substance, motions, and 

 organs. 



i. With regard to its insertion, or articulation with the 

 manitrunk and abdomen, it may be observed that it is 

 attached to both by its whole circumference by means of 

 ligament ; in the Coleoptera, Orthoptera, and Heteropte- 

 rous Hemiptera being received by the posterior cavity of 

 the prothorax, the shield of which in these Orders, espe- 



* Plate XXVII. Fig. 31 . b Plate XV. Fig. 5, 6. 

 c Samouelle t. v. /. 4. 



2 N 2 



