228 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



wings; as far as I am aware, their very existence has never been men- 

 tioned anywhere. 



Under such circumstances, and especially in the absence of collections 

 containing some of the foreign generic forms, the task of establishing 

 the indispensable new genera becomes a very difficult one. I have 

 spared no trouble in reading the descriptions of the existing general 

 and hope, as far as lay in my power, to have avoided redescribing old 

 genera under a new name. 



The following table contains all the genera of Bombylidce hitherto 

 found in North America north of Mexico. The genera hitherto recorded 

 as occurring in Mexico, and not found yet in the United States, are: — 



Adelidea Macq., Dipt. Exot., ii, 1, p. 84, for A. flav<\ Jaennicke, from 

 Mexico. According to Schiner (Xovara), this genus is the same as -So- 

 barus Loew, Beitr., iii. 



Anisotamia Macq., Dipt. Exot., ii, 1, p. 81, for A. eximia {—Anthrax 

 valida Wied.), is closely related to Oncodocera. Whether it is a true 

 a genus established by Macquart for certain African species, remains 

 Anisotamia, to be proved. 



Poecilognathus Jaennicke is simply &Phthiria. 



In using this table, it must be borne in mind that I have not seen 

 Aphoebantus Lw. and Leptochilus Lw., and have placed thetn according 

 to the data of the descriptions; and that I do not know the male sex of 

 Comastcs. 



Analytical table of the genera of Bombylidce, occurring in North America 



north of Mexico. 



1 (10). The bifurcation of the second and third veins takes place oppo- 

 site, or nearly opposite, the small cross- vein ; the second vein 

 forms a knee at its origin from the praefurca; the third vein 

 is in a straight line with the praefurca : 



2 (5). Three submarginal cells, the anterior branch of the third vein 



being connected with the second vein by a recurrent cross- 

 vein : 



3 (4). Antennas with a more or less long style at the end of the third 



joint Exoprosopa Macq. 



4 (3). Antennae without any distinct style at the end, Dipalta nov. gen. 



5 (2). Two submarginal cells: 



6 (7). Third antennal joint with a distinct pencil of hairs at the tip; 



pulvilli distinct Argyramceba Schiner. 



7 (6). Third antennal joint without pencil of hairs at the tip: 



8 (9). Pulvilli distinct Hemipenthes Loew, Centur.^ 



9 (8). No distinct pulvilli Anthrax Scopoli. 



10 (1). The bifurcation of the second and third veins takes place some 



distance before the small cross- vein, at an acute angle ; the 

 second vein does not form a knee at its origin from the 

 praefurca : 



