PSYCHE. 



139 



out their whole extent, so far as I have 

 examined them, and their insect fauna 

 is considerable as may be inferred. 

 The wagon road from Las Cruces or 

 El Paso to the Sacramento Mts. skirts 

 the edge of the Sands for some lo miles. 

 Some few plants and insects collected 

 along the edge, while passing them, 

 have shown a very large percentage of 

 new forms — new varieties among the 

 plants, and new species among the 

 insects. Such an extensive region, 

 possessing such marliedlv peculiar char- 

 acteristics, and unique conditions of 

 environment, must truly have a flora 

 and fauna of its own. Tlie region 

 promises great retmiis to the investi- 

 gator of its flora and fauna. But 

 water is extremely scarce in the vicin- 

 ity, and the heat and glare are almost 

 unbearable in the svunmer months, so 

 much so that travellers always pass the 

 .Sands if possible at night. It there- 

 fore requires more than ordinary cour- 

 age to attempt an investigation at this 

 season. The best months to visit the 

 locality are October and November. 

 Mflny plants are then to be found in 

 bloom on the Sands, and the heat 

 while still verj' great is within the 

 limits of endurance. 



The present paper is the result of the 

 determination of a small Jot of diptera 

 taken by the writer on the edge of the 

 Sands at White Water Holes, and on 

 the plain close by, during a couple of 

 hours collecting on the afternoon of 

 Oct. 6, 1S96. White Water Holes, 

 which sometimes contain a brackish 

 water but are often drv, are situated on 



the road within a few feet of the high 

 banks which form the edge of the 

 Sands. They are about 7 miles north 

 from Lunas well (Pelman's ranch), 

 and 40 miles from Tularosa. 



All specimens with locality White 

 .Sands were taken a short distance over 

 the sand hills from White Water Holes, 

 and actually within the area of the 

 .Sands. All those with locality White 

 Water Holes were taken on the plain a 

 few yards from the edge of the sands. 

 Not more than a half hour, in the late 

 afternoon, was spent within the limits 

 of the Sands, and the area covered was 

 not more than 100 j-ards in diameter. 



The reader is referred, for other notes 

 on the White Sands, to the writer's 

 second paper on the biogeography of 

 Mexico and the Southwestern U. S. 

 (Trans. Texas Acad. Sci., 1S97.) 



I. Paragiis bicolor Fab. var. testa- 

 ceits Meig. Two ? s, and three ^ s, 

 near edge of Sands, at White Water 

 Holes, Oct. 6. On flowers of Asier 

 farvijloriis Gray. Length, 5 to 6 

 mm. All constant in the color of the 

 abdomen. The black is confined to 

 the first segment, and anterior corners 

 of second. The males have the first 

 segment wholly black, but both females 

 have an elongate transverse marking 

 of red on hind margin of first segment 

 in middle. All have at least a brownisii 

 trace of the blackish annulus on hind 

 tibiae. 



Williston says that P. bicolor has a 

 distinct vertical glabrous stripe on the 

 eyes. It really has three such stripes, 

 the other two being on anterior and 



