294 DIPTERA OP NORTH AMERICA. [PART IV. 



Limnobia replicata Lin. This step was taken by Dr. Schiner 

 (Wiener Ent. Monatschr. 1863, and Fauna Austriaca, 1864). 

 He pointed out this relationship, proposed for these species the 

 new genera Triogma and Phalacrocera, and gave to the whole 

 group the name of Limnobina cylindrotomiformia. 



In 1865 (Proc. Entom. Soc. Philad. Vol. IV, p. 224) I de- 

 scribed for the first time North American insects of this group ; 

 four species, belonging to the three above-named genera. The 

 position assigned to the Cylindrotomina in the present publica- 

 tion differs from that which they occupy in Dr. Schiner's work, 

 among the Limnobina anomala. This change of place is intended 

 to indicate the affinities between the Cylindrotomina and the 

 Tipulina ; it has the further advantage of removing the Cylin- 

 drotomina from among the spurless Tipulidae, and placing them 

 in the midst of those which are provided with spurs. 



3. Distribution in Genera. 



Dr. Schiner has distributed the European Cylindrotomina 

 among three genera: Triogma, with one species (T. trisulcata 

 Schum.) ; Phalacrocera, with P. replicata L., and Cylindrotoma 

 with C. distinctissima M., glabrata M., nigriventris Loew, and 

 diver sa Walk. C. glabrata, however, by the structure of its 

 antennas, of its male forceps, and by its venation, is sufficiently 

 distinct from C. distinctissima to be set up as a separate genus. 

 The two remaining species of Cylindrotoma I have not seen, but 

 judging from the description of one of them, C. nigriventris, it 

 is closely allied to C. distinctissima. 



Among the North American species we have in Triogma ex- 

 sculpta 0. S. a form closely analogous with T. trisulcata; in 

 Cylindrotoma americana 0. S. a form almost identical with 

 C. distinctissima. The coloring of C. nodicornis 0. S. is so 

 much like that of the European C. glabrata, that, at first glance, 

 they might be taken for the same species ; and one is surprised 

 to find, upon examination, that they show not unimportant differ- 

 ences in the structure of the antennas, of the male genitals, 1 and 

 in the venation of the wings. The forceps of C. nodicornis 0. S., 



1 I have seen but one dry specimen of C. glabrata, % , and can but im- 

 perfectly judge of its forceps. It would be interesting to investigate 

 whether it is really so different from the typical form of the Cylindrotomina 

 as it appears to me. 



