150 PROCEEDINGS OF THE ACADEMY OF [Feb., 



Mestobregma obliterata Brunei-. 



A single female from Albuquerque, September 14, is referred to this 

 species. 



Mestobregma plattei (Thomas). 



Three males and one female of this species were taken at Silver City, 

 July 20; two females also being included in the series from the lower 

 slopes of the Florida Mountains, taken July 19. At Silver City it was 

 captured on low rounded hills, while in the Florida range it was found 

 sparingly on bare precipitous rocks, where it was noticed to be very 

 vigorous and wary. 



These specimens show some approach to the closely allied M . rubri- 

 penne from southern Arizona, but the general coloration is nearer 

 plattei, while the slender caudal femora are not at all like the compara- 

 tively robust ones of rubripenne. 



The range of this species is now known to extend from Wyoming 

 south along the eastern side of the Rocky Mountains to Colorado, 

 occurring also at Magdalena, New Mexico, and the localities given above. 



DEROTMEMA Scudder. 

 Derotmema laticinctum Scudder. 



This characteristic species of the desert regions of southern New 

 Mexico and Arizona was captured at all the desert localities visited in 

 southern New Mexico and at El Paso. In the vicinity of El Paso it 

 was taken, July 10, 11 and 17, on irrigated land along the Rio Grande 

 (1 cT, 3 9), at the edge of the mesa, (1 cT), in the greasewood belt 

 (1 9 ), in bare desert east of city (2 d\ 2 9 ), on desert hillside (2 d\ 

 1 9 ), on sand with a sparse growth of dry grass (17 d\ 8 9 ). At 

 Alamogordo a single male was attracted to light, July 12; three males 

 were collected in the rabbit-weed and mesquite plain around Deming, 

 July 18; one male and two females secured at Silver City, July 20, and 

 eight males and six females taken at Aden, July 21. 



In the irrigated tract near El Paso the species was fairly common on 

 the barer spots, usually in colonies, while at the foot of the mesa it was 

 not common on pieces of bare ground. At Aden the species was found 

 chiefly in grass prairie land, but in other situations as well, such as on 

 cinders along the railroad track where it was inactive until the sun had 

 warmed the ground, when the species became very active. 



The El Paso specimens from sand area with dry grass are the largest 

 of the species seen, a typical male and female measuring as follows : 



c? 9 



Length of body, 15.2 mm. 25.5 mm. 



Length of pronotum, 3 " 4.8" 



Length of tegmen, 17.5 " 24.5 " 



Length of caudal femur, 10.2 " 14.2 " 



