352 TABANID.E 



5 (6) Vertex with a tuft of black hairs behind the ocelli. Eather 



large species. Middle tibise conspicuously pubescent. Palpi 

 blackish orange. 2 tropicus. 



a (b) Abdomen considerably brownish red. tropicus. 



b (a) Abdomen hardly at all brownish red. var. hisignatus. 



6 (5) Vertex without any tuft of black hairs behind the ocelli. Eather 



small species. Middle tibise only moderately pubescent. Eyes 

 with short pale pubescence. Palpi whitish. 3 montanus. 



7 (4) Frontal triangle shining black. 4 luridus. 



8 (3) Abdomen mainly bright brownish or reddish orange with a black 



dorsal stripe. 



9 (10) Eeddish coloring always extended to the fourth segment, and that 



segment bearing soft pale yellow short pubescence. 



5 distinguendus. 



10 (9) Eeddish coloring almost always extended to the third segment 



only, and the fourth segment with mainly black short 



pubescence. 6 solstitialis. 



Some of the species of Therioplectes are very difficult to name with certainty 

 either from descriptions or from single specimens. There can be no doubt about 

 T. micans or the female of 1\ luridus. and the two reddish species {T. distinguendus 

 and T. solstitialis) are easily distinguished from the others though not from each 

 other, even though I am not sure but that there may be some close connection 

 between the females of T. solstitialis and T. troincus. T. tropicus (as I understand 

 it) is a rather larger species than either T. montanus or T. luridus (though one 

 female from Herefordshire and several continental specimens which I possess hardly 

 bear this out) and may be known from either by the distinct little tuft of black 

 hairs behind the ocelli, as well as by its middle tibite being far more pubescent than 

 those of T. montanus. T. montanus is (according to a large number of specimens I 

 have seen) very variable in the coloring of the abdomen of the female, but may be 

 known by the short pale pubescence of the eyes, and the shorter pubescence on the 

 middle tibise and basal joint of the antennae, a? well as by the short frontal 

 pubescence and the absence of any postocellar tuft of black hairs. T. boreal is has 

 been recorded from Scotland but (as I have said in the synonymical notes under 

 T. montanus) I think incorrectly ; it might however occur there, and should be 

 distinguished by the distinctly pale hindmargins to the abdominal segments. 



1. T. micans Meigen. Legs entirely black ; front tarsi of the male 

 with peculiar long hairs. Frontal triangle shining black. 



A rather large species, distinguished from any British 

 species of the genus Tabanus (sens, lat.) by its hairy eyes and 

 black legs. 



^. Head not remarkably large in comparison with the thorax and abdomen. 

 Frontal triangle small, moderately shining black, quite bare, but with traces 

 of greyish brown dust about the upper angle and in the antennal sockets and 

 sometimes about the sides ; face with broad side-cheeks which are pale grey 

 in some lights but dark slaty grey in others, and these side-cheeks are all 

 covered with long dense pubescence which is blackish near the eyes but 

 whitish grey on just the inner sides, and which there partly overhangs the 

 recessed epistoma ; the actual margin against the eyes is whitish grey from 

 the level of the antennte down the face and round to two-thirds of the way up 

 the back of the head ; in profile the face protrudes from the eyes to the 

 lower angle of the mouth but is shallow beneath the eyes, and the head is 



