156 DIPTERA OF NORTH AMERICA. [PART II. 



on both tarsi it is rather singularly at right angles with the fourth 

 joint, is somewhat longer than the third joint and has the form of 

 a slender club. The grayish-hyaline wings are rather long and 

 narrow ; their anal angle is rather rounded off; the last segment 

 of the fourth longitudinal vein runs upon its middle over a dis- 

 tinct convexity of the wing and is there a little inflected ; towards 

 its end it does not much approach the third longitudinal vein, 

 which is here very gently curved backwards ; the sixth longitudi- 

 nal vein becomes entirely indistinct at a considerable distance 

 from the margin of the wing. 



Hob. Venezuela. (Moritz.) 



Observation. Although the present species differs in some re- 

 spects from Eutarsus aulicus, still it coincides in many important 

 characters with it, so that it cannot be located into any other 

 genus, unless, rather prematurely, a new genus is created for it. 

 Eutarsus aulicus approaches the forms which prevail in the genus 

 Diaphorus more than the above described species. 



Gen. XXVIII. DIAPHORUS. 



At the time of its adoption, and long after, the genus Diaphorus 

 was considered as one which was very distinct from the genus 

 Chrysotus. The characters which Meigen uses for their dis- 

 tinction are the following : for Chrysotus, arista apical, the eyes 

 of the male contiguous under the antennae, and the wings some- 

 what divaricated when in repose ; for Diaphorus, arista dorsal, 

 eyes of the male contiguous on the front, and the wings reposing 

 upon each other when at rest. 



The more species of these two genera have become known and 

 the more carefully they have been examined, the more unsatisfac- 

 tory Meigen's characters have been found. North America is 

 particularly rich in species belonging here, but showing important 

 structural deviations. 



Besides the species showing a different structure of the thorax, 

 and which were formerly classed with Chrysotus, but are united 

 now in the genus Chrysotimus, the other species of Chrysotus, . 

 agreeing in their habitus, are divided in such, the males of which 

 have eyes contiguous under the antenna?, and in- such, where the 

 eyes are separated by the sometimes broad face ; the position of 



