1918] Aldrich — Notes on Diptera 35 



given by Knab as 1897 in Science for January 14, 1916, — presum- 

 ably he took it from specimens sent by Johnson to Coquillett for 

 determination. The earliest date on specimens in the collections of 

 the Illinois State Laboratory of Natural History is August, 1908, 

 and Tucker reported it from Kansas in the same year (Kans. Acad. 

 Sci., xxii, 278, 1908), but probably collected it earlier. In the 

 Pacific Northwest, I collected a specimen at Pendleton, Ore., on 

 May 19, 1907; Mr. Wm. M. Mann secured two at Wawawai, 

 Wash., on Aug. 30, 1908; and it was common on carrot flowers at 

 Moscow, Idaho, on Sept. 4, 1908. It was in Arizona in 1910 (C. 

 N. Ainslie, Proc. Ent. Soc. Wash., xiii, 118). These items may be 

 of service in tracing the spread of the species. 



(h) I am indebted to W. H. Dall, of the National Museum, for 

 further information about the Psilopus of Poli, 1795. which was 

 long supposed to preoccupy the same name as applied to a genus 

 in the Dolichopodida?. Poll's large work, "Testacea utriusque 

 Siciliee," is unique as a taxonomic effort, in that the writer used a 

 complete double set of names, — a genus and species for each kind of 

 shell, and an entirely different genus and species for the soft parts 

 of the same mollusc. Thus the system is tetranomial rather than 

 binomial, and Dr. Dall informs me that it is considered by taxono- 

 mists in Mollusca to be entirely outside of nomenclature; he added 

 in reply to my question that he was not aware of any controversy 

 whatever on the point. This is the same point of view expressed 

 by Sherborn in Index Animalium, noted by me in Canadian En- 

 tomologist, 1910, 100. Since it seems that Poll's work is the same 

 nomenclaturally as if it had never been wTitten, there can be no ob- 

 jection to the use of Psilopus by Meigen in 1824. 



In this connection it may be well to add that the distinctions 

 upon which I based Gnamptopsilopus 1893, and recognized Agono- 

 soma as distinct from Psilopodinus in my Catalogue of 1905, break 

 down entirely in the oriental region ; so I would not include all in 

 Psilopus. 



