307 



Head retractile, narrow ; dorsal slits very narrow, ventral one broad 

 and extending so far forward that the labium is divided centrally; 

 antennae very short and stout ; labrum obtuse at apex ; maxillae stout, 

 palpi very robust, nearly as thick as the maxillae and slightly shorter ; 

 mandibles stout, slightly curved, their apices obtusely rounded, teeth 

 short, rounded, 3 in number, all on a median protuberance ; labium 

 divided in center, the sides without distinct teeth. Body cylindrical, 

 covered with dense decumbent pile, segments longer than broad, with 

 the usual transverse incised lines present in Limnobiidae ; apical seg- 

 ment shorter than preapical. its posterior surface oblicjuely truncate, 

 heavily chitinized, the spiracles small and widely separated, situated 

 near upper extremity of the round plate ; ventral blood-gills absent. 



Described from a specimen in the collection of this Laboratory 

 v/hich was taken in a cabbage field at Rose Hill, Cook Co., 111., Sep- 

 tember 26, 1883. 



The round heavily chitinized apical plate is very similar to that of 

 Coenomyia. 



Division BRACHYCERA 



There is a diversity of opinion among systematists regarding the 

 arrangement of the famihes of this division, and while the general 

 scheme in the present paper is essentially the same as that proposed 

 by Brauer it differs in some respects from that of any previously pub- 

 lished classification. The two tribes, Platygenya and Orthogenya, are 

 those used by Brauer, but I have discarded his group names 

 Homeodactyla and Heterodactyla, retaining the superfamily divisions 

 v.hich he indicated, but using names derived from one of the included 

 families in order to conform to the rules governing nomenclature. 

 Both of Brauer's discarded groups — which have a status between his 

 tribe and superfamily — are heterogeneous, and while the present ar- 

 rangement may not be ideal, it appears to me a better and less cumber- 

 some one than Brauer's. 



The classification adopted by Verrall differs in many respects from 

 that of Brauer. and is based entirely on imaginal characters. I can 

 not accept Verrall's linking together of Scenopinidae and Mydaidae 

 in one superfamily in view of the close resemblance between the larvae 

 of the former with those of Therevidae, and consider that they really 

 belong to the same superfamily as Therevidae despite some re- 

 semblances the imagines bear to those of Mydaidae. 



It is unnecessary to go into details regarding the various classifica- 

 tions proposed. A resume of them may be found in Williston's Man- 



