1919.] NATURAL SCIENCES OF PHILADELPHIA. 107 



ranges from grenadine red through bittersweet orange to bitter- 

 sweet pink on one hand, and through light coral red to testaceous 

 on the other hand. 



Distribution. — From Navasota and Hearne, east-central Texas, 

 westward to south-central (Altar Valley and Baboquivari Moun- 

 tains) and central (Fort Whipple) Arizona and southern Nevada 

 (Rioville), and from the Mexican boundary northward typically 

 as far as Hearne, Midland and Amarillo, Texas, and Dimmit Lake 

 and Albuquerque, New Mexico. Material from localities rang- 

 ing from Dallas, Temple, Ira and Clarendon, Texas, northward 

 over central and western Oklahoma to central Kansas (Clarendon, 

 Belpre and Russell) are atypical or clearly intermediate between 

 M. m. maculipennis and M. m. macdungi. 



The southern race of the species, i. e., typical jnaculipennis, 

 is thus seen hardly to encroach upon the humid section of eastern 

 Texas, while westward its distribution is largely controlled by 

 suitable grasslands, these usually in bolson plains or river valleys. 



The vertical distribution of the race is known to extend from 

 approximately sea-level (Corpus Christi and Gregory, Texas) up 

 to at least 5318 feet (Fort Whipple, Arizona). In Texas we know 

 it ranges from the lowest localities here given to approximately 

 4000 feet (Marathon and Kent). The lowest locality we have 

 for it in Arizona is 3200 feet (Palo Alto Ranch). The Oklahoma 

 localities range between 1360 and 2700 feet above sea-level. The 

 present geographic form, and for that matter the species, reaches 

 sea-level only in the Rio Grande Plain, where, under semi-arid 

 conditions, the species apparently reaches its optimum develop- 

 ment. 



Biological Notes. — The occurrence of this species as a whole, 

 as throughout the genus, is governed by the distribution of grass 

 patches or continuous grass prairie. The present race is typically 

 one of arid and semi-arid regions and its favorite environment is 

 associated with a number of dominant types of vegetation, as 

 groves of high mesquite and clump Opuntia in southern Texas, 

 weedy pastures and prairies in the same region, post oak groves 

 in central Texas, associated with cat-claw (Acacia) in west central 

 Texas, and about composites on river plain in the Rio Grande 

 region of western Texas and southern New Mexico. Sun-cured 

 grass is apparently just as attractive to M. mac. maculipennis as 

 the more succulent green vegetation. 



