DIPTERA 241 



together. These fused segments appear as 

 rings, e.g.j Tabanidae. 



Suborder II. Cyclorrhapha. A circular cap is pushed off 

 the pupal case by the bladder-like protrusion, 

 ptilinum, which forms on the anterior part of 

 the head of the imago and this imago escapes 

 through the circular opening thus made. 

 In the imago a curved scar is left when the ptilinum 

 contracts. This scar is the lunule, and the 

 presence of this scar shows that the insect 

 belongs to the Cyclorrhapha. Antennae are 

 short, usually three-jointed, and more or less 

 flattened against the head ,or dependent. 

 The third segment has at the base a bristle or 

 style, arista. 



(1) ASCHIZA. The extremities of the lunule are 



not continued as sutures on each side of the 

 face, e.g., Syrphidae, or hover-flies. 



(2) SCHIZOPHORA. The extremities of the lunule 



are continued as lines on each side of the 

 face, so as to separate off the antennae and 

 mouth-parts from the rest of the face. ' These 

 lines form the frontal suture, e.g., Muscids, 

 Glossinae, Stomoxys. 



Suborder III. Pupipara. Larva nourished within the 

 parent and changed into a pupa without 

 feeding. Some are wingless, in others the 

 wing venation is imperfect. Antennae are 

 small rounded masses showing no division 

 into joints, with one or more stiff hairs ; the 

 claws are powerful and much curved, e.g., 

 Hippoboscidae and sheep-ticks. 



Suborder IV. Siphonaptera, or fleas, are by some con- 

 sidered to be wingless diptera ; but, if so, they 

 are so much modified that they are best 

 considered separately, and will be considered 

 in Part III. in connection with plague. 

 16 



