250 DIPTERA OP NORTH AMERICA. [PART II. 



being also prolonged over the first joint of the tarsi, where the 

 bristles are ranch shorter, and there are about ten bristles in all. 

 As, in other respects, this specimen agrees perfectly with the 

 others, and as the row of bristles in question seems liable to vary 

 as to its closeness, I take this specimen for a variety of P. sipho. 



Observation 2. — It has already been noticed above, that the 

 species described as P. sipho by Macquart, is not synonymous 

 with the present one. "Walker, in the List of Dipt., has also a 

 P. sipho, but as he quotes Macquart's P. sip>ho among the syno- 

 nyms, and as his own P. cjeminifer seems to be nothing else but 

 the P. sijrfio Say, it becomes very doubtful whether the P. sipho 

 of the List of Dipt, is identical with Say's species ; this is the 

 reason why it has been omitted in the synonymy. By all means, 

 as Mr. Walker does not describe his species, it is a matter of 

 indifference what he may have meant by it. 



Observation 3. — The Imperial Museum in Vienna contains two 

 specimens of P. sipho Say, marked as being from New Holland. 

 As there are also two specimens of P. pollens with a similar 

 habitat, one is justified in supposing that these indications are 

 erroneous. 



3. P. scalber Loew. % . — Chalybeus vel viridis, liitidissimus, alarum 

 fasciis duabus irigricantibus, antice conjunctis et postice abbreviatis, 

 facie nuda, pedibus in utroque sexu navis, tarsorum interniediorum maris 

 articulo primo in latere anteriore pilis minutis erectis confertirn ciliato. 



Steel-blue or green, very shining ; wings with two blackish bands, which 

 are connected in front and abbreviated behind ; face without hairs ; feet 

 yellow in both sexes, the first joint of the middle tarsi of the % closely 

 ciliated upon the front side with short, erect, minute hairs. Long. cqrp. 

 0.24. Long. al. 0.24. 



Syn. Psilopus scaber Loew, Neue Beitr. VIII, 85, 2. 



This species is strikingly like P. sipho, but it cannot be taken 

 for its variety in consequence of the structure of the middle tarsi. 

 The above mentioned row of bristles, which the J* of P. sijjho has 

 upon the front side of the middle tibia?, exists also in P. scaber, 

 but is more sparse ; towards the end of the tibiae, it is interrupted, 

 as it evidently appears, not in consequence of the loss of some 

 single bristles. The first joint of the middle tarsi has no bristles 

 whatever upon the front side ; instead of that, there are some quite 

 short, stiff, erect, minute hairs of a blackish color, which form a 



