SYNARTHRUS. 137 



Observation. — Syntormon tarsatus has upon the upper side of 

 the first joint of the antennae, quite in the vicinity of the basis, a 

 few almost imperceptible little hairs, which I am unable to per- 

 ceive in the present species, so that I am compelled to locate it 

 into the genus Synarthrus. It is further distinguished from Syn- 

 tormon tarsatus by the shorter arista and by the broader wings, 

 which are less narrow towards the root. Besides, in the male the 

 tip of the hind tibiae is less thickened, the second joint of the mid- 

 dle tarsi is broader, of a whitish color, and has only at its tip a 

 black margin, while in the male of Syntormon tarsatus it is less 

 broad, yellowish upon the middle of the root and black upon the 

 whole apical half. The relation which exists between Synarthrus 

 palmaris and Syntormon tarsatus is exactly the same as that be- 

 tween Synarthrus pallipes and Syntormon Zelleri. 



2. S. ciwereiTentris Loew. 9 • — Viridis, coxis anticis pedibusque 

 flavis. 



Green, fore coxa? and feet yellow. Long. corp. 0.13. Long. al. 0.13. 



Syn. Synarthrus cinereiventris Loew, Neue Beitr. VIII, 48, 1. 



Female. Shining metallic-green. Pace very broad ; the infe- 

 rior portion protrudes considerable in the shape of a roof, so that 

 the palpi are rather concealed and the mouth becomes unusually 

 large ; the blue-green ground color of the face is rather covered 

 by a gray- whitish powder. Antennae black, rather large for a 

 female ; the second joint overreaches the inner side of the third 

 with a broad lobe ; the third joint is short, but very broad, beset 

 with very short but distinct hair ; the arista is distinctly longer 

 than the antennae. The front in the middle is almost blackish- 

 green, about the antennae steel-blue, on the upper corners rather 

 violet and may possibly vary a little in its coloring. Cilia of the 

 upper orbit black, those of the lateral and inferior orbits white. 

 Thorax shining metallic-green, with very thin and almost imper- 

 ceptible, nearly whitish, dust. Abdomen also shining metallic- 

 green, on the lateral margin with but little perceptible whitish, 

 powder. Tenter whitish-gray. Fore coxae yellow, with delicate 

 whitish hair and no black hairs or bristles. Middle and hind 

 coxae blackish with yellow tip, the former green on the front side, 

 and, like the fore coxae, beset with delicate whitish little hairs. 

 Feet yellow ; tarsi gradually dark brown towards their end, but 



