GRASSHOPPERS — GURNET AND BROOKS 11 



Variation: Seven representative males, measured in millimeters, 

 vary in pronotal length from 3.3 to 4,5 (average, 4.0), in length of hind 

 femur from 9.5 to 13.0 (av. 11.3), and in length of tegmen from 13.2 

 to 19.0 (av. 16.0). The smallest male is from Atoyac, Mexico, the 

 largest ones from Mt. Alvarez, Mexico, and 18 miles north of Alpine, 

 Tex. Three measured females vary in pronotal length from 4.3 to 

 5.1 (av. 4.7), in length of hind femm* from 12.4 to 13.5 (av. 12.8), 

 and in length of tegmen from 17.0 to 21.0 (av. 18.7). The tegmina of 

 most specimens exceed the hind femur by about the maximum width 

 of hind femur, by somewhat more than that in a few specimens, while 

 in one specimen (north of Tehuac^n) the tegmina reach only to the 

 femoral apices. Most, but not all, specimens collected within the 

 past 20 years have pink hind tibiae, but in most old specimens and a 

 few recent ones the hind tibiae are ash or greenish gray. Apparently 

 some variation occurs in nature, though killing agents and the condi- 

 tions of preservation may be responsibile for some loss of color. 



The shape of the dorsal valve of aedeagus is variable in dry prepara- 

 tions, due to shriveling. The membrane along the anterior margin 

 then often becomes indistinct and the margin becomes irregular, 

 sometimes indented. The lateral process is of uniform length, for the 

 most part, but is below average length in the male from Alpine, Tex. 

 The dorsal shoulder at the base of the apical "scoop" of the dorsal 

 ovipositor valve is somewhat variable, occasionally more angular 

 than in fig. 10, g. 



Distribution: The map (fig. 4) shows the distribution oimexicanus, 

 based on specimens examined. Two lots of Texas specimens have 

 been examined: 4 miles west of Ft. Stockton, Pecos Co., Aug. 8, 1955, 

 J. R. Hilliard (2 cf , 39) ; in Jeff Davis Co. 18 miles north of Alpine, June 

 19, 1939, F. B. Isely (1 cf). Hebard (1917 ; 1932a) listed other Mexican lo- 

 calities, but only one Mexican State, Queretaro, additional to those on 

 the map, is represented by those records. It is probable that all or most 

 localities represented by Bruner's specimens (1908) were reported 

 by Hebard because he acquired Bruner's collection of North American 

 Orthoptera. Hebard (1925b) did not report mexicanus from Sinaloa, 

 but collections from northwestern Mexico, in general, have not been 

 extensive. More collecting is needed to determine the distribution 

 of mexicanus in Texas, but the paucity of records suggests scarcity 

 or localized occurrence. Tinkham (1948, p. 619) had no records 

 other than to repeat the El Paso record of atlanis by Rehn and Hebard 

 (1909) . El Paso specimens have not been examined, but they probably 

 represent M. bilituratus defectus. 



Biology: No detailed information on the biology of mexicanus is 

 available. The data on the specimens examined show occurrence in 

 central Nuevo Le6n at altitudes of both 2,200 and 7,000-8,000 feet. 



