2i8 The Ohio Naturalist. [Vol. V, No. 2, 



later it has been possible to get together a large and representa- 

 tive collection from the region covered by this paper. Through 

 correspondence with Miss Gertrude Ricardo who has studied 

 Bigot's types and also the Tabanidae of the British Museum I 

 have gained much. She has even redescribed several of Bigot's 

 types for me and by this means I have satisfactorily identified a 

 number of his species. 



The European material I have for comparison consists of a 

 large number of species acquired by exchange with Prof. Morio 

 Bezzi of Italy, Dr. K. Kertesz of the Hungarian National Museum 

 and E. Brunetti of England. In comparing one is convinced, 

 with Dr. Loew, that hardly any of the species of the two countries 

 seem to be exactly the same but in some cases they are very close. 



Since I have been studying this family I have visited The 

 Museum of Camparative Zoology, The U. S. National Museum 

 and The Museums of Kansas University and The University of 

 Illinois. At each place I was given every opportvmity to study 

 the contained material and am under obligations for these 

 privileges. 



In most cases under each species only those characters of 

 most consequence in determination are mentioned. 



Kcv to the North American Genera. 



1. Hind tibiie with spurs at the tip 2 

 Hind tibi;E without spurs 6 



2. Third segment of the antenna composed of eight annuU the first 



of which is only a Uttle longer than the following ones 3 



Third segment of the antenna composed of only five annuli the 

 first of which is much longer than the following ones; ocelli 

 present 5 



3. Front of female narrow ; ocelli present or absent ; fourth posterior 



cell at least open Pangonia* 



Front of female broad with a denuded callus; ocelli present 4 



4 Eyes in the female acutely angulated above; wing in both sexes 



\vith a dark picture Goniops 



Eyes in the female not acutely angvilated above; wings hya- 



"line -4 patolestes 



5. Second segment of the antenna about half as long as the first ; 



eyes in life with numerous small dots Silvius 



Second segment of the antenna as long or but little shorter than 

 the first ; wing with a dark picture CJirysops 



6. Third segment of the antenna with a well developed basal 



process Tabanus'\ 



Third segment of the antenna without, or with a rudimentary 

 basal process 7 



7. All the tibi?e enlarged, the hind pair ciliate Snowiellus 

 None of the tibiae enlarged and the hind pair not ciliate 8 



8. Front of the female as broad as long the callus transverse Hcematopota 

 Front of the female narrow Diachlorus 



* Including Diatomineura and Corizoneura. 

 t Including Atylotus and Therioplectes. 



