THE SYRPHIDAE OF OHIO j. 



thickened; larger, pilose species. (3) The Cerinae, a small group, differ- 

 ing from all the others in having a terminal style rather than a dorsal arista 

 on the antennae. 



Williston further divides these sub-families into fourteen tribes 

 which, while they doubtless show many true relationships, are by no 

 means alwa3'S satisfactory. 



Verrall in his work on British Flies makes seven sub-families; u.sing 

 besides the ones mentioned above, Volucdlinae, Milesinae, Chryso'toxhiae 

 and Microdontinae. 



GEOGRAPHICAL DISTRIBUTION 



In general both genera and species in this family are widely distrib- 

 uted. There are about 2^000 described species from all parts of the world. 

 Of these over 300, belonging to about 60 genera, occur in America north 

 of Mexico. Only about 5 or 6 genera are restricted to America; 42 are com- 

 mon to Europe and North America, and nearly 40 species are known to 

 be common to these two continents. It is my behefthat this latter number 

 will be augmented considerably when examples from the two continents 

 are more carefully studied. At any rate I can see no essential differences 

 between the descriptions by \^errall of certain species from Great Britain, 

 and the descriptions of others under dift'erent names from North America. 



As is shown by so many other biological groups, the distribution of 

 the species in this family indicates greater resemblance between the 

 Pacific and European faunas than between the Atlantic and European. 



Forty-one genera and about 113 species are listed in the present paper 

 as actually collected in the State. Many of these species are widespread, 

 not only in the State but over large parts of the country. A number are 

 found on other continents as Paragus tibialis, P. bicolor, Platychirzis pclta- 

 his, Melanostoma mclliiiiim, Syrphus torviis, S. rihesii, S. grossulariae, 

 Eristnlis aetteus d.nd Syriita; pipieiis 2ind a few (notably Eristalis tenax) 

 are cosmopolitan. Others are much restricted in the State; for example 

 the species of Microdon have been taken in the State only near Cincinnati. 



GEOLOGICAE DISTRIBUTION 



A number of fossil insects of this family have been worked out by 

 Dr. S. H. Scudder from American Tertiary beds. These belong prepon- 

 derantly to the vSyrphinae, or the group with the basal cro.ss-vein. The 

 following genera are definitely recognized: Syrp/iics (abundant). C/ii- 

 losia^ Clnysogastei\ Rhiugia, Sphegina and probably /'//-/.r^?. In addition 

 a fo.ssil Microdo)! was four.d at Aix, and the following genera have been 



