232 DIPTERA Or NORTII AMERICA. [PART II. 



tolerably well with the two sexes of a species from Cuba, described 

 below as P. chrysoprasius, although the face of the male of this spe- 

 cies is distinctly covered with dust and the halteres are blackish 

 with a dark yellowish-gray knob. But it evidently results from the 

 statements of Fabricius, that his P. longicornis belongs to those spe- 

 cies, the arista of which is very elongated and but little shorter thau 

 the rest of the body. In P. chrysoprasius, on the contrary, the arista 

 is not even as long as head and thorax together. Thus the latter 

 species must be considered distinct from that of Fabricius, as long 

 as their identity has not been proved by the comparison of typical 

 specimens. In Winthem's collection there is a male specimen, 

 marked P. longicornis, and designated as Wiedemanu's type ; it is 

 P. chrysoprasius. As Wiedemann, in the description of P. longi- 

 cornis, refers only to the specimen from the collection of Fabricius, 

 it is evident that Winthem's specimen came only later in the pos- 

 session of Wiedemann, and was probably named by him P. longi- 

 cornis, after comparison with his own description. This is no proof 

 at all of the identity of the genuine P. longicornis Fabr. with P. 

 chrysoprasius. The specimen in the collection of Fabricius can alone 

 afford light upon this subject. 



2. sipho Say. The frequent occurrence of the species described below 



under this name, and the characters which result from a compari- 

 son of Say's and Wiedemann's descriptions, leave me no doubt 

 about the correctness of my determination. That Say did not dis- 

 tinguish it from P. sealer, a very closely related, but more rare 

 species, results from the fact that there are two specimens in Wiede- 

 mann's collection, namely, a male of P. scaber, and another of P. 

 sipho, both communicated under the latter name by Say himself. 

 The name which Say has given belongs naturally to tbe common 

 species. The species which Macquart (in Dipt. exot. If, 2, 119) 

 described as P. sipho, is an entirely different species, probably the 

 one which I described below as P. jucundus, from Cuba ; however, 

 it may also represent a mixture of several species, as the localities 

 of its occurrence (Pennsylvania, Cuba, Guyana and Brazil) seem to 

 indicate. 



3. unifasciatus Say. Say describes this species without stating the sex, 



Wiedemann as P. Sayi, after a male specimen, obtained from Say. 

 As there is no sufficient ground for the change in the name of the 

 species, introduced by Wiedemann, the name given by Say must be 

 restored. This species certainly belongs to those with pale-colored 

 cilia of the tegulse. I know three North American species which 

 answer more or less Say's description with regard to the color of the 

 body ; in all three only the first joints of the antennae are yellowish, 

 the third joint, however, brown ; thus all three could not be iden- 

 tified with P. unifasciatus Say, if his statement, " antennce whitish," 

 were to be taken literally, which certainly ought not to be done. 



