86 NORTH AMERICAN DIPTERA. 



In this family are placed several wingless forms, or 

 those with the wings more or less rudimentary. One of 

 the former is Chionea, the species of which are found on 

 snow, often in the coldest weather. 



The family Tipulidae is easily divided into three sub- 

 families, which I prefer to call the Ptychopterinse, Ivim- 

 nobiinse and Tipulinse, and which correspond precisely 

 with the Ptychopterina, Tipulidae brevipalpi and Tipu- 

 lidae longipalpi of Osten Sacken. 



The following table is chiefly based upon that of Osten 

 Sacken in his monograph, which will be indispensable to 

 the student. The nomenclature of the venation is that 

 of Osten Sacken. 



TABLE OF GENERA. 



1. Seventh longitudinal vein present, that is there are two longitud- 



inal veins between the fifth vein and the posterior margin of the 

 wing. ........... 2 



Seventh longitudinal vein absent; no distinct V-shaped suture on 

 mesonotum. ...... Ptychopterinse. 



2. Last joint of the palpi shorter or not much longer than the two pre- 



ceding together; the auxiliary vein usually ends in the costa and 

 is connected with the first longitudinal vein by a distinct cross- 

 vein; antennae six to sixteen jointed, rarely more. Limnobiinse 

 Last joint of the palpi whiplash-like, much longer than the three 

 preceding together; antennas rarely with more than thirteen 

 joints; the auxiliary vein ends in the first longitudinal vein by 

 an abrupt curvature at the tip, not connected with the first vein 

 by a cross- vein ........ Tipulinse. 



1. Wingless, spider-like in appearance. . . . Chionea. 

 Winged. ........... 2 



2. A single submarginal cell present. ...... 3 



Two submarginal cells present (one in Goniomyia manca.} . 5 



3. Antennae i4-jointed. ...... Limnobiini. 



Antennae i6-jointed. ........ 4 



