290 



DIPTERA OF NORTH AMERICA. 



[PART IV/ 



The Cylindrotomina possess other characters, however, which 

 are foreign to the Tip. brevipalpi. 



1. The Cylindrotomina have a single submarginal cell and 

 spurs at the tip of the tibise. The Tip. brevipalpi with a single 

 submarginal cell, as far as known, never have any spurs on the 

 tibiae. 1 The presence of these spurs is a point of affinity to the 

 Tipulina. The divaricated spurs of Phalacrocera remind very 

 much of Tipula. 



2. The course of the veins immediately surrounding the stigma 

 is very peculiar here. The first longitudinal vein, instead of end- 

 ing in the costa, is incurved towards the second vein, and ends in 

 it (fig. 4). The marginal cross-vein (usually connecting the first 

 and second longitudinal veins and thus dividing the marginal 

 cell in two sections) is absent ; instead of it, there is a short, 

 generally oblique and often indistinct cross-vein between the first 

 vein and the costa (fig. 4 a) ; this cross-vein is inserted a short 

 distance anterior to the tip of the first vein. A glance at the 

 venation of a genuine Tipula (fig. 6) at once shows its homologies 



with that of the Cylindrotomina. 

 In Tipula the second longitudinal 

 vein has a short fork (fig. 6, 6, c), 

 which is wanting in the Cylindro- 

 tomina; the first vein ends in the 

 anterior branch of this fork ; the 

 prolongation of this anterior 

 branch, together with a short 

 cross-vein (a) between the first 

 vein and the costa (which cross- 

 vein is homologous to the above- 

 mentioned cross-vein of the Cyl- 

 indrotomina) inclose a small tra- 

 pezoidal cell, very characteristic 

 of the Tipulina (fig. 6, between 

 a and b). To complete the re- 

 semblance, it would be necessary 

 for the second vein of the Cylin- 

 drotomina to emit a short branch ; and this is actually the case 

 with the European species Phalacrocera replicata (fig. 5), where 



Fig. 4. 



Compare the genus Atarba, which may he an exception. 



