ENTOMOLOGY. 121 



some instances the hind legs are most developed, and 

 are far most employed in furthering the insect's 

 economy. This may be witnessed in the pill-rolling 

 beetles, (Ateucki.) 



We have now briefly considered two of the princi- 

 pal sections of the body, the head and thorax, and it 

 only remains for us to bestow a similar notice on the 

 third, namely, the ABDOMEN. This portion is at once 

 known by the absence of all external articulated ap- 

 pendages similar to those of the anterior segments, 

 and a greater simplicity of composition, consisting 

 merely of several consecutive horny segments or 

 rings, in all cases closely joined, and in some in- 

 stances overlapping each other. The greatest amount 

 of these segments is nine ; for the entire number in 

 an insect never exceeds thirteen, and of these one 

 is formed by the head, and three are occupied by 

 the thorax. It often happens, however, that the 

 number seems much less, in consequence of several 

 being united, or so overlapping each other that they 

 cannot be observed. In general the dorsal segments 

 seem more numerous than the ventral ; although 

 the reverse of this obtains in some instances. A 

 difference in this respect is not unfrequently a sexual 

 distinction. The shape is too various to admit of a 

 determinate definition in a few words, but a trans- 

 verse section very generally makes an approach to a 

 rectangular triangle, the base being uppermost. The 

 mode of attachment to the thorax is nearly the same 

 in all cases, although there is an apparent difference 

 depending on the shape of the basal portion. When 

 the latter is broad, as in conical shaped abdomens 



