1896.] ENTOMOLOGICAL NEWS. 1 53 



to make it the type of a new genus. I have refrained from this, 

 however, because the limits of the genera Porphyrops, Rhaphhim 

 and Xiphandrium are by no means perfectly definite (Conf. 

 Schiner Fauna Austriaca Diptera i, p. 194) and the founding of 

 a new genus could only add to the confusion. A careful study 

 of the structure of the hypopygium in these genera may give 

 more satisfactory characters, but the small size of the species and 

 the difficulty of obtaining sufficient material will, I fear, delay 

 such a study for some time. Adopting Schiner's definition of 

 the genera Rhaphium and Porphyrops^-\i^ abandons Loew's 

 genus Xiphandrium — I am in doubt where to place the American 

 species; I prefer, therefore, to accept Loew's view and to recog- 

 nize his ^enus as distinct from the other two. 



The second species may be placed without difficulty in Wahl- 

 berg's genus Thinophilus as defined by Loew (Monog. ii, p. 

 148-149) and Schiner. According to Loew the male Thinophilus 

 has six, the female five abdominal segments, whereas Schiner 

 says that the abdomen is "in beiden Geschlechtern fimfringlig." 

 The latter author also claims that the first and second abdominal 

 segments are of equal length. Neither of Schiner's characters 

 will apply to the American species, and here, too, I suspect 

 that Loew is the more accurate. 



The American Thinophilus is remarkable in two respects. 

 First, its occurrence in the Western States and its absence in the 

 Atlantic States — for I can hardly believe that so large and con- 

 spicuous a Dolichopodid could have been overlooked in the 

 latter region — is another example of the similarity of the fauna 

 of the Western States to that of Europe. Baron Osten Sacken 

 long ago called attention to this interesting resemblance in the 

 distribution of several insects (see his Western Diptera, p. 351 

 et seq.). A second peculiarity of the American Thinophilus \s 

 its occurrence in Wyoming, far from the sea-shore or any body 

 of salt water. The European species ( T. flavipes Zettst. , rufi- 

 cornis Haliday and versutus Walk. ) are described as occurring 

 along the sea-shore. Concerning this interesting difference in 

 the American form, two suggestions may be made: either the 

 species has become adapted to living along the shores of alkali 

 streams and ponds, or it may be actually a salt water species 

 which has its center of distribution in the vicinity of the Great 

 Salt Lake. These are matters for further investigation. 



