12 CLASS INSECTA. 



nary division being once established, naturally presented 

 themselves to the mind, and it was the celebrated Professor 

 Nitzch who first adopted them. Some naturalists have since 

 given the name of collar (collare) to the prothorax or anterior 

 segment, which bears the first two feet. Desirous of preserv- 

 ing the denomination of corslet, but at the same time of re- 

 straining its application within just limits, we shall use it in 

 all cases where this segment considerably surpasses the others 

 in size, or where the latter are united with the abdomen, and 

 appear to constitute an integrant part of it. This is peculiar 

 to the coleoptera, the orthoptera, and to many hemiptera. 

 When the prothorax, being short, forms with the follow- 

 ing segments a common and visible mass, the trunk thus 

 composed of three united segments, shall preserve the deno- 

 mination of thorax. We shall continue to call the lower 

 surface of the trunk, the breast dividing it according to the 

 segments into three areas, the fore-breast, the middle-breast, 

 and the hind-breast. The medial line shall be the sternum, 

 which again we shall divide into three parts, the fore- 

 sternum, the middle-sternum, and the hind-sternum. 



The teguments of the thoracic segments, as well as those 

 of the abdominal segments, are generally divided into two 

 rings or semi-rings, one dorsal or upper, the other lower, and 

 united laterally by means of a soft and flexible membrane, 

 which is in fact nothing but a portion of the same teguments, 



thus all the segments of the thorax will have each one pan- of stigmata, 

 but of which those of themetathorax are not very visible, or are obliterated in 

 the hymenoptera or diptera, and the two posterior or metathoracic ones, 

 are situated on the segment which comes immediately after that which 

 bears the second wings. In the orthoptera, the hymenoptera, the lepi- 

 doptera, and the diptera, the two anterior or prothoracic, are placed 

 between the prothorax and the mesothorax. The abdomen will be com- 

 posed of nine complete segments, the last three of which compose the 

 organs of generation. 



