THE CORSELET. 25 



abdomen behind, I shall terra the corselet ('). Unlike 

 the head, this part is composed of several distinct rings 

 and pieces, which have but recently received names, 

 and been studied. Most of the names invented by our 

 English authors are confused, inappropriate, and bad. 

 In following M. Audouin, I shall endeavour to be as 

 plain and simple as I can. 



The most natural division of the corselet is into 

 three rings or segments, though these are sometimes 

 very distinct, and sometimes intimately united. These 

 three rings, beginning from the neck, may be termed 

 the fore-corselet , the mid-corselet, and the hind-cor- 

 selet( 2 ), which three being united, form the corselet. 

 It will be convenient to consider, that the whole cor- 

 selet, as well as its three rings, has a breast, two sides, 

 and a back. 



The student must be warned, that, among the nume- 

 rous species of insects, these several parts are found to 

 be very variable in size ; and, agreeable to the interest- 

 ing law, that as one part is enlarged, another is pro- 

 portionally diminished, it is not unusual for a par- 

 ticular part to be exceedingly minute, or wholly 

 wanting, if a contiguous part be comparatively very 

 large. 



Taking the whole corselet, and beginning at the 

 breast, we find a piece which may be appropriately 

 termed the breast-plate ( 3 ), and is found in all insects, 

 forming sometimes a large, sometimes a small piece, 

 in some species very distinct, as in several water- 

 beetles, but in others so intimately united to the con- 

 tiguous pieces, that the joining is imperceptible. The 

 breast-plate forms the middle of the breast in all the 

 three rings of the corselet, and for the sake of more 

 minute distinction, it may be considered as divided 



(1) In Latin, Thorax. 



(2) In Latin, Prothorax, Mesathorax, Metathnrtue. 

 (3) In Latin, Sternum, which is inaccurate. 



