154 Annals Entomological Society of America [Vol. IV, 



their respective localities. D. W. Coquillett, Chas. W. John- 

 son, J. M. Aldrich and other Dipterologists have aided in vari- 

 ous ways. One finds it much pleasanter to work at a difficult 

 task when he meets with such encouragement as I have had in 

 this study. 



The characters available for the separation of the species in 

 both of these genera are rather meager and I doubt not that 

 students will experience more or less difficulty in using the keys 

 and descriptions. The differences which distinguish species 

 are sufficiently evident, however, for the purpose when the 

 proper comparisons can be made, but without the opportunity 

 to make comparisons as is the case when a single species is 

 considered one may not always feel satisfied with results. 



I was not able to get all of the described species from Mex- 

 ico and Central America but where I possessed specimens of 

 species from these countries they are included in the consid- 

 eration of their respective genera. 



A list of the species and synonymy is given below but the 

 reader is referred to Aldrich's Catalogue of North American 

 Diptera and to other works for further references to literature. 



List of the Species of Proctacanthus. 

 arno Townsend, Proc. Cal. Acad. Sci. IV. 599. 



brevipennis Wiedemann, Auss. z\v., I, 431. Van der Wvilp, Tijdsch. 

 v. Ent., XXV, Ids. Williston, Trans. Amer. Ent. Soc. XII, 73. 

 caudatus new species. 

 coquillettii new species, 

 duryi new species. 

 fulviventris Macquart, Dipt. Exot., Suppl. IV, 88. Osten Sacken, Cat- 



alogue 235, note. 

 heros Wiedemann, Auss. zw., I, 427. Schiner, Verh. Zool. Bot. Ges., 

 1866, 682; 1N<>7, 390. Williston, Trans. Amer. Ent. Soc., XII, 74. 

 longus Wiedemann, Dipt. Exot., 183; Auss. zw., I, 42(i. Macquart, 

 Hist. Natur. Dipt., I, 307; Dipt. Exot., I, 2, 123. Schiner, Verh. 

 Zool. Bot. Ges., 1866, 682; L867, 396. 

 eraverii Bellardi, Saggio, II, 50. Williston, Biologia, Dipt., I, 327. 

 micans Schiner, Verh. Zool. Bot. Ges., 1S67, 397. 

 milbertii Macquart, Dipt. Exot., I, 2, 124. 



missouriensis Riley, 2d Mo. Report, 122, fig. 89. 

 Pagrion Jaennicke, Neue Exot. Dipt., 57. 

 nigriventris Macquart, Dipt. Exot., I, 2, 124. 

 nigrofemoratus new species. 

 occidentalis new species. 

 philadelphicus Macquart, Dipt. Exot., I, 2, 123. Williston, Trans. Am. 



Ent. Soc, XII, 75. 

 rufiventris Macquart, Dipt. Exot., I, 2, 123, plate X, figure 2. 

 rufus Williston, Trans. Am. Ent. Soc, XII, 74. 



