30 OHIO STATE ACADEMY OP SCIENCE. 



Front. The anterior surface of the head between the eyes and 

 above the antennae. 



Frontal callosity. A prominence slightly above the antennae, pres- 

 ent in the female sex only. It varies in form and coloration. 



Hyaline triangle. The hyaline patch beyond the outer border 

 of the cross-band in Chrysops. 



Ocelli. The simple eyes are present in many species and absent 

 in others. 



Ocelligeroiis tubercle. A prominence in some species of the 

 genus Tabanus where the simple eyes would naturally occur. 

 There are no simple eyes in our species of the genus. 



Palpi. These are the only organs included under mouth parts 

 not considered as belonging to the proboscis. They are prom- 

 inent and vary in form and coloration. 



Proboscis. The mouth parts other than the palpi taken collec- 

 tively. The labium forms a sheath for the others. 



Pulvilli. A pair of pads or cushions located one beneath each 

 claw at the distal end of each last tarsal segment. Of the 

 three pads seen in this location the two outer are pulvilli and 

 the middle one is the empodium. 



Stigma. A darker patch in the wing in the region of the union of 

 the second vein with the costa. 



Subcallus. The part of the front between the antennae and the 

 frontal callosity. It is denuded in some species. In others 

 it is denuded in the female and pollinose in the male. 



Tegulae. Two membranous lobes at the base of the wing. Shown 

 in Plate II. 



Wing. Reference to Plate II will give an understanding of the 

 parts and regions of the wing. 



FAMILY CHARACTERS. 



The family Tabanidae includes medium sized to large insects 

 commonly called horseflies, gadflies, deerflies, dogflies, earflies 

 and various other names. Usually its members are readily recog- 

 nized at sight by their form and general appearance. 



The three jointed antennae with the third joint annulated 

 and without a style or arista, the rather large tegula, and the 

 well developed pulviliform empodia taken together serve to dis- 

 tinguish them from other flies in case of any doubt. 



None of the species are really small ; the head is large, larger 

 and hemispherical in the male, smaller and somewhat flattened 

 in the female. 



The antenncX are porrect and composed of three segments 

 of which the third is compound, having five or eight annulations, 

 when there are eight the basal one is only slightly longer than 



