THE CANADIAN ENTOMOLOGIST. 215 



western Syrphids in general, and what is well known in regard to boih 

 animals and plants, viz., the agreement of Pacific species with those of 

 Europe. If, as Williston has suggested, the course of the distribution in 

 this family has been Irom west to east, British Columbia would seem to 

 be in the path of distribution. In this connection it is worthy of note that 

 there is found a much larger number of eastern species in British 

 Columbia than in California or elsewhere on the west coast. However, 

 in the present state of our knowledge, this latter fact may bear another 

 interpretation. The mountain passes are much lower to the northward 

 and the region of high altitude is much narrower. There is also distinctly 

 more vegetation, and •these conditions would make the passage of eastern 

 species westward easier toward the north, and this might account for the 

 greater number of eastern species than is found farther southward. The 

 number of species of the genus Syrphus (17) in this list is somewhat 

 remarkable j 13 are known from Alaska. The west is far richer in this 

 genus than the east. For instance. New jersey, which has been carefully 

 worked, has 8 species. The same thing is noticeable in the genera 

 PiatychirKS, Chiiosia, Sphcerophoria and Melanostoma. On the other 

 hand, the common eastern genera, Pipiza, Xanthogramma, Spiloinyia and 

 Tenmo stoma, have not thus far been noted in British Columbia. 



In the preparation of this paper the writer has had the opportunity 

 of comparing with types and identified material in the National Museum 

 at Washington, in the Museum of Comparative Zoology at Cambridge, 

 Mass., and in the American Museum of Natural History at New York, 

 thanks to Curators Coquillett, Henshaw and Beutenmuller. 



A number of species still remain undetermined, and some of these are 

 apparently new. These will not be listed here, but will await publication 

 until such time as a careful comparison with the literature of European 

 species can be made in order to avoid needless duplication of specific 

 names in a family already too rich in synonyms. In the following list all 

 material not otherv/ise indicated has been taken by the writer ; 



I. Microdon tristis, Loew. — -A single female specimen in my 

 collection, bearing the data ■' Br. Col., June 16, 189S," seems to belong 

 here, although it is larger than the eastern tristis, the fourth segment of 

 the abdomen is nearly bare, the pile of the front and vertex is black, and 

 the tibiae and tarsi are brownish-red instead of reddish-yellow. It 

 approaches most nearly to the variety cothiirnatus, Bigot, which has been 

 recorded from Oregon. 



