OF THE TABAXID.E OF THE UNITED STATES. 467 



49. Tabanus socius n. sp. ■=. exi^WW^.O^, 



Female. Is very like T. offinis ; it will be sufficient to indicate the differences. Smaller 

 in size, being only 1-j-lG mm. loni^- ; the coloring- of the dark jwrtions is of a lighter gray, 

 sonie^vhat slate color ; the second joint of the palpi is shorter and much stouter at the base, 

 the color of the palpi is paler ; antenna; of a lighter red, last joint but very little infuscated 

 towards the end ; the yellowish brown at the base of the front tibiti; is more extended here, 

 in many specimens the tiliia^ are black at the tip only; the front is distinctly coarctate 

 anteriorly, but narrower than in T.affinis; the linear i>ru]ongation of the callus in most 

 specimens forms a slightly elevated ridge, sometimes nearl\' reaching the ocellar tubercle. 

 Length, 15-16 mm. I have about a dozen of specimens from the northwestern parts of 

 the Hudson's Bay Territory (Fort Simpson, Kennicott), agreeing in these characters; also 

 two specimens from Illinois. All these specimens have the antealar tubercle reddish. 



This species is most remarkaljly like the common European T. tropkns ; however, a 

 specimen of the latter in the Museum of Comparative Zoology, labelletl by Dr. Loew, has 

 a somewhat broader front, the antealar tubercles black, the antenniw somewhat more brown- 

 ish at the tip. I sent a specimen of T. socius to Dr. Loew, who declared it to be different 

 from his T. trojiicns. 



There seems to be a good deal of uncertainty connected with the European species of 

 this group. Dr. Schiner, Fauna Austr., Diptera, I, p. 30-31, makes iropicifs (non Linne) 

 Loew = sohtidaUs (Meig.) Schiner; tropicus (Limie) Schiner = Jurldus {won YaWhw) 

 Loew; ixwdi lurldus Fallen (non Loew) =^ tropicus V-m\7.qy. Loew observes (Verb. Zool. 

 Bot. Ges., 1858, p. 580), in a note to the description of T. tropicus, that '■ the difficulties 

 concerning this species are increased by the fact that there are evidently several other 

 species yet coming in conflict here, which cannot be distinguished with certainty in single 

 specimens." Similar difficulties proljably exist among the North American species. 



T. vlcbuis Macq., Dipt. Exot., I, 1, p. 143, 41 (^Carolina) apparently belongs in this 

 relationship. 



50. Tabanus septentrionalis. 



Tabanus scpt<:ntrionalis Loow, Verb. Zuol. Bot., 1858, p. 593. 



I translate Dr. Loew's description : 



"Female. Ex-cinereo niirricans. abdomine trifuriam cinereo maculato, maculis lateralibus 

 obliquis, margini postico vix contiguis, ti))iis ol)Scure testaceis, oeulis hirtis, trifasciatis. paljiis 

 nigropilosis, antennis nigris, frontis callo infero et liuea longitudinali media atris. Long. 

 Corp. lin. ; long. al. 5J lin. 



''(Cinereous blackish, abdomen with three rows of cinereous spots, the lateral ones 

 oblique, hardly touching the hind margin, tibia3 dark testaceous, eyes hairy, with three 

 stripes, palpi with black hairs, antennte black ; frontal callosity and a longitudinal line in 

 the middle, black; length 13 nnn.) 



"The great uniformity which prevails through the whole dipterous fauna in the arctic 

 regions, and the resemblance between T. septentrionalis and the two preceding species,^ 



^T. quatuornotatus Muig. and nUjiicornia Zctt. 



