OSTEN SACKEN ON WESTERN DIPTERA. 269 



specimens; unfortunately, none of my species is represented in both 

 sexes. 



The two genera recently described by Dr. Loew, and compared by him 

 to Apatomyza, Prorachthes from Syria (Berl. Ent. Monatsschr., 1868, 380), 

 and Heterotropus from Turkestan (Beschr. Eur. Dipt., iii. 180) are very 

 different from Epibates. Prorachthes differs in the shape of the abdomen, 

 the position of the head, the structure of face and front, of the first 

 antennal joint, the venation; Heterotropus has short palpi and no 

 spines on the legs. Kone of them has the peculiar muricate points on 

 the thorax. 



I have six species belonging to the same group, but unfortunately 

 only one specimen of each ; four of them are males, and two females ; 

 thus I am able to describe only one sex of each species ; and this has 

 to be borne in mind in reading my descriptions of the generic as well as 

 specific characters. The presence of the sharp points on the thorax of 

 the males of E. luctifer, funestus, harrisi, and muricatus proves that 

 they are congeners ; the position of E. marginatum and magnns in the 

 same genus rests on characters taken from the other parts of the body. 

 Mac-quart does not say anything of the presence of sharp points on the 

 thorax of his Apatomyza nigra $ ; bat they are easily overlooked in all 

 the species except in the large E. muricatus. 



Epibates, in Greek, means a passenger. 



The characters of Epibates are as follows : — 



Head on the same level with the thorax, and not much broader; occi- 

 put moderately convex, more so in the females {E. marglnatus and 

 magnus). 



Eyes contiguous in the male for a short distance only, the apex of the 

 vertical triangle being very much drawn out; ocellar tubercle distinct; 

 the ocelli are placed on its sides, and for this reason, in the male, very 

 difficult to perceive ; in the two females, the eyes are separated by a 

 broad iuterval ; on each side of the ocellar tubercle, an ocellus is dis- 

 tinctly visible, but I do not perceive the third one (in E. muricatus, 

 male, the eyes are separated by a very narrow interval). 



Face and lower part of front subconically projecting in the profile ; on 

 the upper side of this projection, the antennse are inserted ; the interval 

 between their base and the margin of the mouth (the epistoma or face) 

 is narrow, sloping; the head descends but little under the eyes ; oral 

 opening oval, oblique, moderately large (Macquart's figure, Dipt. 

 Exot, ii, 1, tab. 11, f. 1, a, showing the head in profile, is exaggerated, 

 and the eyes are made to reach too low). 



Proboscis longer by about one-half than the vertical diameter of the 

 head ; lips distinctly marked; palpi more than half as long as the pro- 

 boscis; first joint ribbon-shaped, two or three times the length of the 

 second, which is somewhat lanceolate. 



Antennce shorter than the head ; first joint subcylindrical ; second not 

 much longer than it is broad, subcyathiform ; the third about equal to 



