306 DIPTERA OF NORTH AMERICA. [PART IV. 



Cylindrotomina, to form a separate genus. (Compare the gene- 

 ral remarks on the genera of this section, p. 295.) 



The head is somewhat attenuated posteriorly ; the palpi of P. 

 tipulina have the last joint elongated, longer than the two, but 

 shorter than the three preceding taken together. The first joint 

 of the antennae is cylindrical, elongated ; the second cyathiform ; 

 the joints of the flagellum (in P. tipulina) are elongated, cylin- 

 drical, slightly incrassated near the basis ; the verticils are upon 

 this incrassation, and therefore before the middle of the joint. 

 These antennae have exactly the same structure as the antennas 

 of many Tipulse. In P. replicata, the joints of the flagellum are 

 not incrassated at the basis, and the exceedingly short verticillate 

 hairs are inserted in the middle of the joint ; thus the likeness to 

 Tipula is not so striking. Besides the verticils, the antennae of 

 the male of P. tipulina have & Sense, delicate pubescence. The 

 collare is somewhat more developed and broader in P. tipulina 

 than in P. replicata. The thorax has the stout, compact shape, 

 common to the Cylindrotomina; the thoracic suture is well 

 marked, grooved in the middle, more shallow on the sides ; the 

 intervals between the thoracic stripes are somewhat depressed, 

 but shallow and not marked with a groove or with conspicuous 

 punctures ; two distinct impressions at the basis of the scutellum. 

 Feet long and rather strong ; spurs long, divaricate ; empodia 

 distinct ; last joint of the tarsi in the male distinctly excised at 

 the basis on the under side. 



The forceps of the male is very much like that of Cylindrotoma ; 

 the claw-shaped horny appendages are turned, in the state of 

 repose, towards the upper anterior margin of the abdominal seg- 

 ment ; the aculeus consists of three horny. styles, connate at the 

 basis, sharp and pointed at the tip (I have seen only the aculeus 

 of P. tipulina). The ovipositor of P. replicata, according to Dr. 

 Schiner, is short, with broad foliaceous valves. 



The venation is somewhat different in the two only known 

 species. The difference in the course of the first longitudinal vein 

 has been alluded to above ; I have also shown before, when speak- 

 ing of the general characters of the Cylindrotomina (p. 290), 

 that it would be perhaps a more correct interpretation of the 

 course of the first vein of P. replicata, if we considered this vein 

 as ending in the second vein, and the latter emitting a branch 

 towards the anterior margin. The venation of P. replicata viewed 



