108 PROCEEDINGS OF THE ACADEMY OF [March, 



The period of adult occurrence is slightly more than four months, 

 the earliest date being June 12 (CotuUa, Texas), the latest Octo- 

 ber 16 (El Paso, Texas). At Marathon, Texas, it occurs adult 

 as early as July 1 and as late as September 2; Rehn and Hebard 

 have reported it from El Paso as early as July 10 and we now 

 have it as late as October 16 from the same locality, while we 

 have from the adjacent Mesilla region of New Mexico material 

 taken June 28 and 30. The span of the spec'es in the adult con- 

 dition for any one locality can be safely set at about three months. 

 The only immature specimens we have before us were taken July 8 

 (Spofford and Johnstone, Texas) and August 14 to 16 (Dallas), 

 at the latter locality accompanied by adults. 



Remarks. — This race, the typical form of the species, is almost 

 entirely one of the semi-arid and arid grasslands of the south- 

 western United States, occurring in its extreme development in 

 such situations in the Rio Grande Plain and Fayette Prairie region 

 of Texas, as well as in the bolson plains and river valleys of the 

 southern portions of New Mexico, Arizona and Nevada. South- 

 ward and in the Rio Grande region it shows especially pronounced 

 attenuation in form, while Arizona and Nevada material, limited 

 in number though it is, shows a relatively more robust form, re- 

 taining, however, the other characteristics of the race. The 

 optimum development of the species is apparently reached in 

 south-central Texas, although the pair from southern Nevada is 

 very large. In northern Texas the material of this race is less 

 typical, the form somewhat shorter proportionately, the head 

 blunter in general form and the pronotum not as elongate, nor 

 the caudal angle of the disk of the same of the typical broadly 

 rounded condition. As material from more northern localities 

 is examined, the divergence from the southern type becomes more 

 pronounced, until in Nebraska and in western Kansas we have 

 typical mac. macclungi, which is apparently a more northern 

 Great Plains and Great Basin representative of maculipemiis, 

 clearly intergrading, as stated above, when material from inter- 

 vening regions is examined. 



In every series of any size of atypical or intermediate material, 

 certain specimens showing instability and, to a greater or lesser 

 degree, the characters of one or the other extreme will be en- 

 countered. This is particularly pronounced in the three indi- 

 viduals from Amarillo, Texas, one male of which is essentially 

 typical m.. maculipemiis, while the remaining pair are clearly 



