54 



NORTH AMERICAN DIPTKRA. 



OSTEN SACKEN'S CLASSIFICATION. 



Osten Sacken has offered many pertinent criticisms of 

 Brauer's classification, insisting that the Nemocera and 

 Brachycera are divisions of more fundamental importance 

 than was assigned to them by Brauer. His classification, 

 so far as it was developed by him, is as follows: 



Suborder Orthorrhapha Nematocera. Palpi usually four or five-jointed, 

 pendulous and more or less filiform. Antennae many jointed (more 

 than six-jointed), usually filiform (seldom pectinate), with the 

 majority of the joints of the flagellum homologous (homomor- 

 phous) . 



Superfamily Nemocera Vera. Males dichoptic;* no bisection or 

 bicoloration of the eyes. Antennae provided with sensitive hairs 

 arranged symmetrically on the flagellum in verticils or pencils 

 (except Mycetophilidse) . No pulvilli;t empodia often, but 

 not always present. 



A. Larvae peripneustic,| always terrestrial. Cecidomyidae, My- 

 cetophilidae. 



B. Larvae peripneustic or amphipneustic, aquatic, subaquatic, 

 sometimes terrestrial. Culicidae, Chironomidae, Psychodidae, 

 Dixidae, Tipulidae. 



Superfamily Nemocera Anomala. Diptera with homologous (ho- 

 momorphous) joints to the flagellum; usually four-jointed paipi. 

 Males frequently holoptic, sometimes the females also. Pulvilli 

 usually present. Antennae withoiit sensitive hairs. Ocelli usually 

 present. Bibionidae, Simulidae, Blepharoceridae. Rhyphidaa, 

 Orphnephilidae. 



Suborder Orthorrhapha Brachycera. Palpi not more than two-jointed, 

 not pendulous, the end joint more or less clavate, and larger than 

 the basal one; joints of the antennal flagellum, with rare excep- 

 tions, not homologous. 



Superfamily Eremochaeta. No macrochaetae. Three well developed 

 pulvilli. Males predominately holoptic, the eyes often bisected. 

 Antennal flagellum polymorphous. Axillary incision, alula and 

 antitegula in most cases distinctly developed. Discal cell usual- 



*They are sometimes truly holoptic. 



tRecent investigations show that true pulvilli are sometimes present. 



J Amphipneustic larvae are those in which the spiracles are con- 

 fined to the first and last segments: metapneustic those in which they 

 are confined to the posterior segments; peripncnstic those in which 

 they are present on the median rings. 



