1919.] NATURAL SCIENCES OF PHILADELPHIA. 75 



Length of Length of Length of Length of 



body. pronotum. tegmen. caudal femur. 



Kerrville, Texas 33 4.9 23.5 19.5 



Kerrville, Texas 35.5 5.3 24.3 20 



Cisco, Texas 33.1 4.8 23.3 18.9 



Cisco, Texas 37.7 5.8 26.5 22 



Amarillo, Texas 32 4.9 22.5 18.1 



Amarillo, Texas 32.5 4.9 22.4 19 



Marathon, Texas 30.6 4.6 21 17 



Marathon, Texas 35.6 5.5 24.8 • 21 



Sycamore Canyon, Baboquivari 



Mountains, Arizona 31.3 5 22 18.2 



Sycamore Canyon, Baboquivari 



Mountains, Arizona 37 5.7 27.4 21 



9 



Hot Springs, South Dakota 36.5 6 23 20 



Havana, lUinois 38.6 5.5 24.8 21 



Hamburg, Iowa 43.7 7 28.3 24.2 



Hamburg, Iowa 44 7 30.5 — 



Southwestern Nebraska 41.2 6.3 26 26.8 



Southwestern Nebraska 41.2 6.2 29 22.4 



Dodge City, Kansas 40.2 6.1 28 23.4 



Dodge City, Kansas 39.7 6 27 ' 23 



Syracuse, Kansas 39.8 6.9 29.2 23.4 



Syracuse, Kansas 50 7.5 31.6 27.4 



Dallas, Texas 45 7.2 31 26.2 



Dallas, Texas 52 7.8 33.4 28.8 



Kerrville, Texas 47.2 7 30.6 24 



Cisco, Texas 46.6 6.5 30 25.3 



Cisco, Texas 52.2 7.5 34 26.9 



Amarillo, Texas 45 6.8 30 25.2 



Marathon, Texas 44.2 6.5 38.3 25.3 



Marathon, Texas 51.2 7.6 32.2 26.4 



Northeastern New Mexico (type) .. .37.3 7 25.5 22.4 

 Sycamore Canyon, Baboquivari 



Mountains, Arizona 50.5 8 33 26.2 



Sycamore Canyon, Baboquivari 



Mountains, Arizona 51 7.8 33.2 26.9 



From these measurements it is quite apparent that the species 

 shows minimum size at the more northern and more eastern locali- 

 ties and the maximum size southward, at least as far as its dis- 

 tribution within the United States is concerned. Immediate 

 environment appears to us to be an extremely potent factor in 

 influencing the size of individuals, those from the relatively poorly 

 grassed Great Plains regions being of small size, excepting when 

 from the more heavily carpeted swales and valleys. The material 

 from the Illinois sand areas, the most eastern locality known for 

 the species, is of very small size, well illustrating the response of 

 the species to a rather unfavorable environment. The optimum 

 size development of the species is reached in northeastern Texas 

 and south-central Oklahoma, with grassland areas of western 

 Texas (Marathon) and southern Arizona (Sycamore Canyon), 

 following in the large size of their representatives. 



