from the Sacramento and White Mountains. 147 



mens occur, showing three or even four strong bristles on 

 sides of face near orbits. One female has three on one side 

 and four on the other, the latter making a continuous row 

 with the descending frontal bristles ; another female shows 

 only one bristle on one side and two on the other, while still 

 another female shows but one on each side. The third an- 

 tennal joint in male is usually more widened apically, some- 

 times very strongly so. In one female the third antennal 

 joint is pale reddish, with rest of antenna black. 



Also one female. White Mountain, 9500 feet, July 6 

 [Wooton). In this specimen the second antennal joint is 

 more reddish than black. 



20. Echinomyia Thomsoni^ Will. 



One hundred and six specimens, as follows : — Sixty-five 

 (eleven males and fifty-four females), Rio Tularosa, below 

 Blazer's Mill, about 6000 feet, Oct. 20, except five of the 

 females taken Oct. K-i, on flowers of Bigelovia graveolens, var. 

 glabrata] twenty-one (twelve males and nine females), Rio 

 Bonito, Austen's Ranch, about 6400 feet, Oct. 17, on flowers 

 of Aster Icevisj L. ; twenty (seven males and thirteen females), 

 Rio Ruidoso, above Bowling's Mill, about 6500 feet, Oct. 15, 

 on flowers of Senecio Douglasii, DC. 



These specimens vary in length from 8 to nearly 14 

 millim. 



The female has two rows of orbital bristles on each side of 

 the front, beside the row of frontal bristles along the vitta, 

 while the male normally has only one row. But males occur 

 having some extra orbital bristles, showing an approach to 

 the two rows of the female. The claws and pulvilli in some 

 males are much shorter also than in others. These secondary 

 sexual characters in the male depend largely for constancy on 

 the size and robustness of the specimens. I believe that all 

 the above-mentioned specimens belong to tliis one species, as 

 they otherwise agree well except for size. In occasional 

 specimens the black of abdomen is somewhat more pronounced, 

 while in others the red shows more conspicuously ; but tliese 

 are merely slight colour-variations, and are, moreover, quite 

 rare. In some specimens the front is golden, while in others 

 it is silvery pollinose. It may also be mentioned that the 

 front tarsi are a little widened in the female. 



There is a very great difierence in size between the most 

 robust specimens and the smallest ones. All the specimens 

 examined, selected from the two extremes in size, show no 

 median macrocha?t£e on first abdominal segment, two median 



