456 DIPTERA CHAP. 



a natural group, but the association with them of the other 

 families mentioned is a mere temporary device. The greatest 

 difficulty is ex]3erienced in deciding on a position for Phoridae, as 

 to which scarcely any two authorities are agreed. 



Series 4. Cyclorrhapha Schizophora, or Eumyiid flies. The antennae consist 

 of three joints and an arista. In tlie Caly|)tratae the frontal suture, 

 or fold over the antennae, is well marked and extends downwards 

 along each side of the face, leaving a distinct lunule over the 

 antennae. In the Acalyptrate Mi^scids the form of the head and 

 of the antennae vary mucli and are less characteristic, but the 

 wings differ from those of Brachycera by their much less complex 

 nervuration. 



Series 5. Pwpijmra. These are flies of abnormal habits, and only found in 

 connection with living Vertebrates, of which they suck the blood 

 (one species, Braula caeca, lives on bees). Many are wingless, 

 or have wings reduced in size. The young are produced alive, 

 full grown, but having still to undergo a metamorphosis. This 

 group consists of a small number of flies of which some are 

 amongst the most aberrant know^l. This is specially the case with 

 the Nycteribiidae. This Section will probably be greatly modified, 

 as it is far from being a natural assemblage.^ 



The Sub-Order Aphaniptera, or Fleas, considered a distinct Order by many 

 entomologists, may for the present be placed as a j)art of Diptera. 



It must lie tidmitted that these sections are far from satis- 

 factory. Brauer divides them into Tribes, based on the nature 

 of the larvae, but these tribes are even more unsatisfactory than 

 the sections, hosts of species Ijeing entirely unknown in the 

 larval state, and many of those that are known having been very 

 inadequately studied. We must admit that the classification of 

 Diptera has at present advanced but little beyond the stage of 

 arranging them in natural families capable of exact definition. 

 We may, however, draw attention to the attempt that is being 

 made by Osten Sacken to remodel the classification of the Nemo- 

 cera and Brachycera by the combination of families into super- 

 families.'' He proposes to divide the Xemocera into two super- 

 families : 1. ISTemocera Vera, including all the families from 

 Cecidomyiidae to Tipulidae ; 2. Nemocera Anomala, consisting of 

 the small families Biljionidae, Simuliidae, Blepharoceridae, Bliy- 

 phidae and Orphnephilidae. 



For Orthorrhapha Brachycera he adopts the following arrange- 



^ For tables of the families of flies the student may refer to Loew, Smithson- 

 Misc. Coll. vi. Art. i. 1862 ; to Brauer, Deiik. Ak. JFicn, xlii. 1880, p. 110 

 (Orthorrhapha only) ; to Williston, Manual of X. American Diptera, 1896 ; to 

 Schiner, Fauna austriaea, Diptera, Vienna, 1860, etc. 



- Berlin, cnt. Zeitschr. xxxvii. 1892, p. 365, and xli. 1897, p. 365. 



