176 



dophagous Syrphidae there are upper and lower chitinized mouth- 

 hooks, which consist of two convergent lateral pieces with a V-shaped 

 anterior extremity and correspond to the pair that are present in 

 Schizophora; but in addition to these there are two to four pairs of 

 small chitinized points or hooks which work horizontally and serve 

 the purpose of grasping prey. The mouth-hooks in Schizophora are 

 not V-shaped and the lower one is absent. These chitinized pieces are 

 less readily distinguishable in the aquatic Syrphidae but are present 

 in modified form, while the mouth-margin is specialized. The an- 

 tennae in all species of the latter family are distinct, usually consisting 

 of a single joint, rarely two, with a pair of short apical processes. The 

 body consists of 12 segments, but the segmentation is indistinct be- 

 cause of the presence of numerous transverse wrinkles or folds in the 

 integument ; the surface of the body in most species bears regularly 

 arranged bristles, which are occasionally upon slight elevations and 

 serve to distinguish the different segments. Pseudopod-like structures 

 are often present on ventral abdominal segments, their apices armed 

 with short bristly hairs. Respiration is by means of prothoracic and 

 anal spiracles, the former occasionally doubtfully functional or appar- 

 ently absent, the latter protruding occasionally in a tube-like appen- 

 dage. 



The larvae of Platypezidae resemble some of the Syrphidae rather 

 closely, and bear a striking resemblance to the anthomyiid subfamily 

 Fanniinae in having fringed projecting processes on the body seg- 

 ments. The more elaborate mouth-parts readily separate them from 

 all Anthomyiidae, and also, in my opinion, associate them more closely 

 with Syrphidae than with Phoridae, though Brauer places them with 

 the latter in the tribe Hypocera. 



The Phoridae are much simpler in general form than most Syr- 

 phidae and all described Platypezidae, possessing, in as far as they are 

 known, no prominent body appendages. The mouth parts are similar 

 to those of the other families of the group in having anteriorly fused 

 mouth-hooks. The larvae are amphipneustic — possessing prothoracic 

 and anal spiracles. 



The transformation to the pupa takes place within the last larval 

 skin. 



Division Schizophora 



The larvae of this group, which contains a great majority of the 

 members of this suborder, are readily distinguished from those of any 

 other order by the remarkable reduction of the head, which, when 

 seen laterally, consists of a V- or U-shaped chitinized posterior plate, 

 which has two posteriorly divergent dorsal rods, and, attached to the 



