22 Mr. C. H. T. Townsend on Diptera 
brown, the labella shining dark brown. Face, thorax, and 
scutellum brassy-yellow pollinose ; abdomen shining tawny 
yellow, the apical portion (in the dried specimen) slightly 
tinged with brownish, but yellow in life. Knobs of halteres 
greenish yellow. Eyes bare, contiguous from the small 
tubercle-like yellow vertex to near base of antenna, leaving 
a small, bare, brassy-yellow pollinose frontal triangle, the 
upper angle abruptly tapered and acute. Anterior branch of 
third vein with a long stump at its basal angle, the stump 
being three times or more the length of basal section of branch. 
Wings, except costal border above mentioned, pure hyaline, 
wholly without sign of spots; veins yellow. The yellow of 
costa reaches from theelongate slightly oblique stigma, which 
is more deeply yellow, to base of wing, filling out the portion 
basad of the basal cells with a tinge of the yellow. Posterior 
cells all open, none of them narrowed, except that fourth is 
narrowed a little on border from its greatest width in middle. 
Difference in size of facets of eye marked, abrupt; the small 
facets extend up to a little short of the anterior or inner angle 
of eye, but the line of separation extends backward from this 
point at a slight upward angle off the horizontal. In life this 
specimen had little of the green tinge, except on the eyes as 
described. 
I give this full description of this very handsome variety 
of a well-known species, because existing descriptions of the 
species are lacking in detail. The points of difference 
between this variety and the typical form, as well as several 
other varieties of meatcanus, are given in the table below. 
A considerable number of forms of this group have been 
described by various early authors—Fabricius, Meigen, De 
Geer, Beauvois, Macquart, and Walker—and classed as 
synonyins of mexicanus (see Osten Sacken, Cat. p. 59). The 
typical form has the wings spotted with brown. Only one of 
the others has the wings absolutely unspotted, namely, 
inanis, Fabr., which I consider a good variety on this 
character. It is at once distinguished from lémonus by the 
tomentum being wholly cinereous instead of yellow. ‘These 
forms should be separated as follows :— 
Table of Tabanus mexicanus and Varieties. 
1. Wings spotted 
Wings wholly without spots ............ 4, 
2. Spots only on cross-veins and bifurcation 
Of third Veiner... /eois a ape isis usje.2e.2ie ee 
Spots also on margin of wing at ends of 
longitudinall-veins >; Vee one. kee olivaceus, De G. 
(S. America.) 
