168 PHYSIOLOGY OF INSECTS. 



costalis, b b, in the lower figure ; the outer portion, the 

 m g k khkhk exterior region or regio exterior, c c c ; 

 T-iWj / faQ i ower portion, the inferior region or 

 regio inferior, d d; and the central 

 portion, the central region or discus, f. 

 These regions have no precise or defi- 

 nite limits, bounded by a constant and 

 uniform margin or nervtire, but are 

 somewhat vague and ideal, yet must be readily understood 

 by a glance at the accompanying figure, a little attention 

 to which will render most descriptions of the numerous 

 cells and regions intelligible. The author should perhaps 

 state, in order to justify in some degree this very meager 

 nomenclature of the parts of the wing, that the nomen- 

 clature of the nervures and cells is at this hour in such a 

 state of unintelligible confusion, that it would occupy 

 more space than this entire volume to unravel the entan- 

 gled synonymy, and render the subject intelligible to a 

 beginner ; he has, therefore, given only those terms and 

 definitions which, though confessedly meager, cannot lead 

 the reader into error. 



Legs. The legs of insects do not undergo the same 

 degree of variation as the wings ; they are of a more 

 uniform structure, not only as regards different kinds of 

 insects, but as regards the legs of the same insects : they 

 are six in number, or three pairs; the fore legs or pro- 

 pedes, which are the pair nearest to the head ; the middle 

 legs or mesopedes ; and the hind legs or metapedes. The 

 natural position of the legs in most insects, when perfectly 

 at rest, is for the fore legs to point forwards ; the middle 

 legs either forwards or backwards, and this dependant a 

 good deal on the will of the insect; and the hind legs 

 backwards; in most beetles the fore legs alone pointing 

 forwards. 



