9i 



PTYCHOPTKRIN^. 



1. First submarginal cell much shorter than the second. Idioplasta. 

 First submarginal cell much longer than the second. . . 2 



2. Three posterior cells (12) ..... Bittacomorpha. 

 Four posterior cells. ..... Ptychoptera. 



1. Legs long and slender, especially the tarsi; anterior branch of the 



second vein absent, obsolete or perpendicular, the rhomboid 

 cell more or less square. ....... 2 



Legs not unusually slender, anterior branch of second vein present 

 and oblique. ......... 5 



2. Antennae thirteen-jointed; male forceps complex. Dolichopeza. 

 Antennas with less than thirteen joints; male forceps small, simple. 3 



3. Fifth posterior cell not in contact with discal cell. Megistocera. 

 Fifth posterior cell in contact with discal cell. ... 4 



4. Head on a neck-like prolongation of the thorax; seventh vein short, 



running into the anal angle. . . . Brachypremna. 



Head more closely applied to the thorax; seventh vein terminates 



in the margin at some distance from the anal angle. Tanyprema 



5. Antennas of $ pectinate or sub-pectinate. .... 6 

 'Antennae not pectinate. ........ 7 



6. Ovipositor of 9 long, sword-like. .... Xiphura. 

 Ovipositor of 9 long but not sword-like (p. So, 4). Ctenophora. 



7. Three posterior veins arising from the discal cell, the two anterior 



sometimes arising together but the petiole always short (p. 80, 7) 



Pachyrrhina. 



Two posterior veins arise from the discal cell, the anterior one fur- 

 cate, petiole always of considerable length. ... 8 



8. Antennas serrate; northern species. . . . Stygeropis. 

 Antennae not serrate below. ....... 9 



9. Marginal vein wanting, but one marginal cell; antennal joints short 



with minute bristles. ...... Holorusia. 



Two marginal cells. ......... 10 



lo.Abdomen slender, very long; antennae composed of twelve joints. 



Longuria. 

 Abdomen less elongate; antennae with thirteen joints (27). 



Tipula. 



