164. MISC. PUBLICATION 305, U. S. DEPT. OF AGRICULTURE 
sary before this could be determined, and it might prove difficult 
even then. 
Tabanus crassicornis Wiedemann, Diptera Exotica, pt. 1, pp. 71-72, 1821. 
Type.—Female, collection unknown. 
Type locality —America ? 
This name is included in the possibility that the type was from 
North America. The description, however, does not fit any Nearctic 
species known to me. 
Tabanus derivatus Walker, List of the Specimens of Dipterous Insects in the 
Collection of the British Museum, pt. 1, p. 151, 1848; Osten Sacken, Smithsn. 
Mise. Collect. No. 270, p. 62, 1878. 
Type.—A male in the British Museum. 
Type locality—North America. | 
Osten Sacken examined the type and did not recognize it. Hine 
examined it and found it to be very close to Tabanus oculus Walker 
and to agree absolutely with another specimen in the British Museum 
collected in Brazil. Since no species of the oculus group occur in the 
Nearctic region, it is not improbable that dertvatus is Neotropical. 
Tabanus difficilis Wiedemann, Aussereuropaische zweifliigelige Insekten, v. 1, 
pp. 165-166, 1828; Szilady, Biologica Hungarica, v. 1, fase. 7, p. 30, 1926. 
Type—Female, originally in the Vienna Museum. 
Type locality —‘Vaterland ?” 
Szilady found a specimen in the Vienna Museum bearing the label 
“Amer. Bor.”, which he claimed to be the type of this species, and 
redescribed it. It is evident from this description that it is one of the 
afinis group with a denuded subcallus, but just which one cannot be 
determined. In an effort to learn more about the specimen the writer 
wrote to the Vienna Museum and learned from Dr. Zerny that the 
specimen could not be found in their collection 
Tabanus dorsonotatus Macquart, Diptéres exotiques nouveaux ou peu connus, 
sup. 2, p. 38, 1847; Osten Sacken, Mem. Boston Soe. Nat. Hist. 2 (pt. 4, 
No. 4) : 478, 1876; Smithsn. Misc. Collect. No. 270, p. 61, 1878. 
Type.—A male, originally in the Bigot collection and perhaps now 
in the British Museum. 
Type locality—Carolina. 
Osten Sacken suggested that this might be the male of Zabanus 
rufus Palisot, which he did not know. Later he examined a 7’. dorso- 
maculatus in the Bigot collection from Carolina, with a label in 
Macquart’s handwriting, which he took to be the type of dorsonotatus. 
This specimen was in such poor condition that recognition was im- 
possible. That this is 7’. fumipennis Wiedemann (rufus Palisot) is not 
likely, judging from the original description. 
Tabanus duplex Walker, List of the Specimens of Dipterous Insects in the 
Collection of the British Museum, pt. 5, sup. 1, p. 173, 1854; Cameron (not 
Walker?), Bull. Ent. Research 17: 26-27, 1926. 
Tabanus imitans Walker, List of the Specimens of Dipterous Insects in the 
Collection of the British Museum, pt. 1, pp. 173-174, 1848. (Preoccupied by 
Tabanus imitans Walker, ibid., p. 146.) 
Cotypes.—A male and a female in the British Museum. 
Cotype locality —St. Martin’s Falls, Albany River, Hudson’s Bay. 
This species, as described, very closely resembles Atylotus peme- 
ticus (Johnson), but the male identified by Hine and described by 
