434 C. R. OSTEN SACKEN'S PRODROME 



Hob. New York, Pennsylvania, Maryland, South Carolina (B. P. Mann) ; Connecticut 

 (Soutliington, in July ; W. FI. Putton). I have three males and two females before me. 



This species is easily distinguished from its relations by the shape of the white abdominal 

 triangles, which are long and narrow, two or three times longer than broad, and not nearly 

 equilateral, as in the other species. The shape of the abdomen is very peculiar, as it ap- 

 pears laterally compressed towards the tip (I did not take note, however, how the abdomen 

 appears in the living specimens). The brown clouds on the wings are less marked in this 

 species than in the three preceding ones ; sometimes they are nearly obsolete. 



The eyes of the female have two rather broad green bands on purple ground ; the lower 

 band at the end is bent toward the upper one ; thus the interval between them, very nar- 

 row near the front, becomes broader at the opposite end. 



T. catenatus Walker (Massachusetts) seems to agree with this species, although the iden- 

 tification is not certain. The variety, described by Walker, Vol. V, p. 172, is a totally 

 different sjjecies. T. recedens Walker, may also be this species ; but the description does 

 not agree so well as that of T. catenatus. 



6. Tabanus abdominalis. 



Tabanits abdominalis Fabricius, Syst. Antl., p. 96, 15. {Museum Dose.) 



? Tabanus abdominalis Palisot Beauvois, Ins., p. 101, Tab. II, f. 4. (1809.) 



f Tabanus abdominalis Wiedemann, Dipt. exot. I, p. 65, 6; Auss. Zw., I, p. 116, 7. 



This species and the next following are either unusually variable, or there are several 

 closely allied species, very difficult to distinguish. With the material which I have before 

 me I am unable to unravel these difficulties, and I believe that they can be solved only by 

 observations made in the localities where these species occur, observations which would 

 define the Hmits of the variation of each species. 



I will first describe here that species, or variety of a species, which I take to be nearest 

 to the original type of Fabricius's description ; and having done this, I will j^i'oceed to de- 

 scribe the different forms which I hq,ve before me, and which may be either mere varieties 

 or distinct species. 



An incidental remark of Macquart's, in the introductory paragraph to the genus Tabanus 

 in th^ first volume of the Dipteres Exotiques (p. 116), throws more light on Fabricius's 

 T. abdominaUs than the author's short descriptions. Macquart names T. abdombialis 

 among the species with a closed first posterior cell. Where did he derive the knowledge of 

 the character ? T. abdominalis does not appear anywhere else in his works, nor is the char- 

 acter mentioned in Fabricius or Wiedemann. The probable and only possible explanation 

 is, that he saw in the Museum of the Jardin des Plantes, the s^DCcimen of Bosc's collection 

 originally described by Fabricius, as expressly stated hi the Sy sterna Antliatorum (Bosc's 

 collection, as well known, is incor2:)orated in that of the Museum). If the specimens from 

 Fabricius's o'wn collection, which Wiedemann described, or his own specimens, had had a 

 closed first posterior cell, that conscientious and careful author would certainly have men- 

 tioned this character, rather imusual among Tabanidoe. Wiedemann's silence proves that 

 the specimens which he saw had the first posterior cell open ; in Palisot's figure that cell is 

 also represented as open ; and, in fact, the specimens with a closed ceU are comparatively 

 rare. 



