April, 1910.] 



Fow Genera oj Horseflies. 



149 



A COMPARATIVE STUDY OF FOUR GENERA OF HORSEFLIES 



James S. Hine. 



The dipterous family Tabanidae contains a number of genera 

 which are not well known on account of the scarcity of material 

 in the museums of the countrs^ A group of four American genera 

 which are nearly related in some respects and which have not 

 been studied in a comparative way are known as Lepidoselaga, 

 Selasoma, Bolbodimyia and Snowiellus. As I have the tvpical 

 species of all of these genera I have selected about a dozen points 

 upon which to make comparison and a brief statement of the 

 results is offered for the purpose of extending acquaintance with 

 these rather extraordinarv members of our American fauna. 



1. Female of Snowiellus atratus, enlarged two diameters; 2, side 

 view of the head of Lepidoselaga lepidota; 3, same of Selasoma tibiale; 

 4, same of Bolbodimyia bicolor: 5, same of Snowiellus atratus. 



The species of all these genera agree in having the wings 

 largely black, the body wholly black, subcalius denuded, pro- 

 boscis short and fleshy, third segment of the antenna composed 

 of five annuli of which the basal is plainly longer than the others 

 taken together, anterior tibia distinctly enlarged, hind tibia 

 ciliate and the anal cell closed and petiolate. Although there 

 are several characters common to all many differences exist and 

 these are best pointed out by considering each genus separatelv. 



Lepidoselaga. Type species L. lepidota from Central and 

 South America. Length about seven millimeters, bodA' shining 

 black with sparse green-refiecting scale-like hairs. The genus 

 was first called Lepiselaga by Macquart in 1S3S and later emend- 

 ed by Loew, according to Osten Sack en. Hadrus of Perty, 



