Dec, 1904.] Tabanidae. 243 



T. rhoinl)icus has been misdetermined by many and conse- 

 quently exists under various names in American collections. The 

 specimens used in this study of the species were compared with 

 Osten Sacken's types and there are before me a long series of 

 specimens agreeing with each of the three forms. Dr. John 

 Marten has described some species of Tabanus in Vol. 14 and 15 

 of the Canadian Entomologist, which seem to correspond with 

 these forms, and after collecting all available information and 

 studying Marten's descriptions carefully, it appears to me that 

 centron is the same as Osten Sacken's second form of rhombicus, 

 and as the latter author did not propose any name, Marten's 

 name remains valid. 



Tabanus rhombicus has the subcallus denuded and no stump 

 on the anterior branch of the third vein. General color of the 

 whole body dark with only a trace of red on the sides of the second 

 and third abdominal segments and three rows of gray pollinose 

 spots. Wings hyaline with traces of fuscous on the borders of 

 the cross-veins and at the furcation of the third vein. Lena^th 

 13 to 15 millimeters. Specimens from Albany Co., Wyoming, 

 collected by E. B. Williamson; from Estes and Manitou Parks 

 Colorado, collected by Dr. F. H. Snow, and from southwestern 

 Colorado, collected bv E. J. Oslar. 



Therioplectes (?) melanorhinus Bigot seems to be this species, 

 judging from the re-description of Bigot's type Miss G. Ricardo 

 has been so kind as to send me. 



Tabanus septentrionalis Loew. This species is somewhat 

 variable in size and coloration but does not appear to be a diffi- 

 cult one to recognize. The subcallus is not denuded; the gray 

 triangles in the middle of the abdominal segments are united to 

 form what may be called a dorsal stripe and on either side of this 

 a prominent row of spots extends from the first to the sixth seg- 

 ment, one spot to each segment. The ground color beneath 

 these spots is often, but not always red., The wings have a dilute 

 yellowish tinge all over and the veins are brown T3ut there is no 

 distinct fuscous margins to the cross-veins or at the furcation of 

 the third vein. Length 13 to 17 millimeters. 



Tabanus sequax WiUiston. The palpi are black, costal cells 

 hyahne, and the stigma and margins of the cross veins and fur- 

 cation of the third vein are also black. On account of the black 

 palpi the species can only be confused with procvon, and the 

 other characters mentioned will separate it from that. Length 

 13 to 16 millimeters. 



Thinking that Bigot's leucophorus was this species, I sent 

 specimens to Miss G. Ricardo who compared with the tvpe and 

 verified my determination. In her letter she makes the following 

 statement: ''The specimen sent on comparison with the type is 

 certainly identical; the tvpe is a trifle larger and the dark li^^CS" 



Lu t L I B R A R Y ] 



