258 



DIPT ERA. 



lateral constriction takes place between the two regions. 

 In the more speciahzed Lepidoptera (butterflies) and 

 in others of the second series of orders, the thorax 

 appears to be constricted vertically, narrowing down- 

 ward posteriorly, to become attached to the abdo- 

 men. A somewhat similar condition is found to exist 

 in the Tipulidae, as seen in Figs. 206, 206, a. As these 



Fig. 206, a. 



flies, like other members of the order, have no sting, 

 it is probable that they do not need the perfectly 

 formed pedunculated abdomen, such as is found in the 

 Hymenoptera Aculeata, and therefore the basal por- 

 tion of the abdomen is not constricted laterally so as 

 to form a pivot-like ring as in bees and wasps. 



