UNRECOGNIZABLE SPECIES AND SYNONYMS. 13 



see, even with a iiiag-nificatioii of over GO, that in many cases the de- 

 scriber, failing to note them, has written a description which might 

 serve equally well for several species. 



In a case of this kind, where one can not definitely decide which 

 species of several was originally described, there are two courses 

 available, failing the production of the types: Either arbitrarily fix 

 on one of the species, or place the name among the unrecognizable 

 species. Of these courses, the latter has been most generally adopted 

 with "Walker's species, and though Coquillett linked up pecunrinn 

 Riley with invenustum Walker, and vittatum Zetterstedt with dec- 

 oruim. Walker, this does not affect the matter of the acceptance of 

 these names, as the first is quite evidently a misidentification of 

 "Walker's species and Zetterstedt's name vHtatum has priority over 

 Walker's decorum. Pecuarum Rilev was described from Louisiana, 

 and the farthest northern record I know for this species is Westville, 

 Conn., Avhile invenustunh Walker was described from St. Martins 

 Falls, Albany River, Hudson Bay, Canada. The specimens which I 

 have seen from Labrador and which may be either Walker's species 

 or that recorded as reptans Linna?us by Lundbeck,^ are undoubtedly 

 not peeuarum. The only species of Walker's which can be accepted 

 with any degree of certainty is ochracewn. In this case the coloration 

 and localit}' prove good guides, and I believe I am correct in identify- 

 ing the specimens from Cordoba as belonging to the species AValker 

 had before him when he wrote his description. 



I am of the opinion that Coquillett was right in making argns 

 Williston a synonym of vittatum Zetterstedt, and have followed him 

 in this. Cinereum Bellardi I have not seen and I am of the opinion 

 that it will be very difficult, if not impossible, to recognize it. In the 

 case of the species mmutum.' Lugger, I believe it is absolutely impos- 

 sible to recognize what species was intended and havo followed 

 Johannsen's synonym}^, and the same applies to that author's species 

 irritafum. Pidchrum Phillipi - I do not consider as identical with 

 tarsale Williston, and I reinstate the latter name. Reptans Linn.Tus 

 I do not believe occurs in America, and I have not included it in my 

 paper. This species is not well defined even in Europe, and I have 

 been unable to identify any American specimens with either of the 

 two species I obtained as reptans from Britain, either or neither of 

 which may be the true reptans. 



Surcouf and Gonzales-Rincones ^ have proposed the specific name 

 minutum for the species described by Dr. Lutz as cxiguum^^ which 

 name is preoccupied by e.rigmim Roubaud."' The specific name minu- 



^ Diptora groenlandlca, 1808. 



- Aiifzuhhin;; dor cliilenlschen DIptoreu, 1865, p. fl".'>. 



"Dipt^'rcs vnln^nintos, vol. 1, 1911, p. 290. 



< Memoirs d. Instltuto Cruz, vol. 1, part 2, 1909, p. 141. 



" Bull. Mus. Paris, 1906, p. 109. 



