Characteristik der Gattungen der Notacanthen. 371 



Macquart forced two heterogeneous species into it (Suppl. I and IV). 

 For this reason, in my Catal. N. Am. Dipt. p. 44, I placed Diphysa 

 ex parte., as a synonym to Exaireta. — Under such circumstances, the 

 name Diphysa be better dropped, the more so as the name was pre- 

 occupied when Macquart used it (Acalepha 1834). 



This history of Diphysa is explained at length in Nowicki's 

 „Beitr. z. Kenntn. d. Dipt. Neuseelands 1875", only the author is not 

 positive enough about the occasion of Macquart's blunder, which 

 was, Wiedemann's erroneous comparison of the venation of 

 his Xyl. spiniger (five post. cells) with that of Beris (four p. c). 



Thorasena (p. 10). This is a parallel case to that of Diphysa, 

 only the developments are still more curious. Macquart (D. E. I, 

 177) established this genus a priori, merely on the strength of 

 Wiedemann's data concerning Hernietia pectoralis Wied. A. Z, II, 

 26 ; but this tirae he went so far as to construct the figure of a fly 

 which he had never seen (1. c. Tab. 21, f. 3 and 3a, the head). Any 

 one who carefully compares the quoted passages and figures will per- 

 ceive, that whatever Macquart gives us, is based on Wiedemann's 

 Statements. Thus ,, Stirn mitten vertieft" is translated ,, front enfonce 

 au milieu", the figure however represents a vertex deeply excavated 

 between the eyes. Dr. B., with an eye upon the figure translates 

 Macquart's french back into german thus (p. 10, No. 34): 



,,Scheitel tief eingesattelt, zwischen den Augen concav", which 

 is rather remote from Wiedemann' s: „Stirn mitten vertieft." I doubt 

 whether Macquart or Dr. B. would have recognized Hermetia pecto- 

 ralis W. in this imaginary Thorasena, with its Asilus-like vertex, 



Pachy stomus. I do not understand why this genus is treated as 

 a distinct form (p. 3, line 16 from bottom; p. 17, No. 115; p. 30, line 9 

 from top) although it is stated on p. 32, line 2 from bottom that it is 

 the same as Xyl. cinctus, and also explained p. 17, No. 115 that the 

 genus was based on a specimen of Xylophagus cinctus with injured 

 antennae? Nevertheless on p. 17 (No. 115) Pachystomus is introduced 

 into the dichotomic table, as having three-jointed antennae! I will recall 

 here that Mr. Bigot (Ann. S. E. 1879, p. 184) gave the same explanation 

 of the origin of Pachystomus. 



Artetnita (p. 7, No. 10). Four scutellar spines are attributed 

 to it, in agreement with Walker, List etc. V, 61, where two species 

 are named as belonging here: Clitellaria Halala (Honduras) and Clitell. 

 Amenides (sine patria). But in the description of Clitell. Amenides 



