190 



18. Antennae short, thick, and often flattened. . .Platyuridae (p. 260). 



— Antennae very long, usually exceeding in length that of body, very 



slender Macroceridae (p. 260). 



19. Mouth parts chitinized, constructed for piercing, not in the form of 



a long slender process Ceratopogonidae (p. 281). 



— Mouth parts not chitinized, fleshy, sometimes in the form of a long 



slender process 20 



20. Radius with 2 branches Sciaridae (p. 258). 



— Radius with 3-4 branches, if less or indistinct the antennal joints 



with very long plumes in the male and very conspicuous constric- 

 tions between them in the female Chironomidae (p. 284). 



Tribe Polykeura 



I have included in this tribe, as I regard it, but one superfamily, 

 Tipuloidea, containing the families Tipulidae, Limnobiidae, Ptychop- 

 teridae, and Rhyphidae. Brauer limited his tribe Polyneura to 

 Tipulidae (inclusive of Limnobiidae), placing the other two families 

 in Eucephala. 



I have placed this tribe first in my arrangement because I consider 

 the adults much more primitive structurally than the most generalized 

 forms in the other groups. The larvae undoubtedly show more special- 

 ization than do those of Mycetophiloidea both in the structure of 

 the head, if we accept the capsule as the criterion, and in the respira- 

 tory system, but I find that the larvae of many closely allied species in 

 different families show quite striking distinctions even though the 

 adults are almost inseparable, and therefore have decided to consider 

 the tribe as more generalized than the others. The sequence of fami- 

 lies does not show an unbroken line, but, rather, represents a series of 

 divergent lines of varying lengths, no two of which start from a com- 

 mon point. 



Superfamily Tipuloidea 



SUPERFAMILY CHARACTERS 



Larva. — Head incomplete posteriorly, wholly or partly retractile, 

 or if the head is complete the abdomen has the anterior 6 segments sub- 

 divided, or the posterior respiratory tube is much elongated and mem- 

 branous, and distinct paired ventral pseudopods are present on anterior 

 half of body. Head with opposed mandibles ; antennae well developed. 



Pupa. — Head without conspicuous armature except in some 

 Limnobiidae ; antennae elongate, curved over upper margin of eyes. 

 Wings and legs closely fused to thorax, the former very short, the 

 latter never extending to apex of abdomen ; thoracic respiratory 



