LVSEC7\4. 17 



prothorax, having no wings and only a pair of legs more 

 or less used in walking, would be proportionately less de- 

 veloped than the metathorax and mesothorax, and also be 

 more independent or less likely to become consolidated 

 with the mesothorax. The cape of the prothorax masks 

 the small size of this ring in the locust, and it is doubtless 

 a special adaptation of the outer folds of the skin for the 

 purposes of protection. How effectively it covers up and 

 defends the vulnerable sutures may be readily observed. 

 The ring inside of this cape is really very small, and it 

 is to this part that we refer, and not to the cape, in 

 the remarks above. The abdomen retains the original 

 conditions of free motion in every direction ; and being 

 without special organs of fliglit or locomotion, has required 

 no special modifications of importance, and retained prob- 

 ably with very little change the primitive mode of segmen- 

 tation or division into simple, unconsolidated rings, except 

 in the terminal segments where the organs of reproduction 

 are developed. 



The junction between the thorax and abdomen 

 should be carefully observed. It is broad and without 

 vertical or lateral constriction. This peculiarity is 

 characteristic of the more generalized insects, and the 

 abdomen has been aptly termed " sessile " to distin- 

 guish it from the pedunculated abdomen of the more 

 specialized Hymenoptera Aculeata (see p. 238). The 

 most obvious characteristic of the abdominal region 

 (PL I., Fig. 3, C) is its division into simple, primitive 

 rings {c^-c^^) . When separated from the metathorax, 

 the first ring (PI. I., Figs. 3, 7, c^) must be closely 

 examined. Its dorsal portion resembles that of the 

 succeeding abdominal rings. It is immovably con- 

 nected with the thorax in front, although behind it 



