28 PROCEEDINGS OF THE NATIONAL MUSEUM vol. no 



Female (allotype): General form as in male, slightly more robust; 

 dijffering as follows: Compound eyes less globose; longitudinal carinae 

 of vertex more widely separated and less prominent; median carina 

 of prozona and metazona proportioned as 21:26, in lateral view some- 

 what more angulate at principal sulcus; mesosternal hump lacking; 

 cercus as in bilituratus dejectus (fig. 10, A); dorsal valve of ovipositor 

 as in figure 10,o. 



Coloration: Somewhat darker than in holotype; hind tibia red. 



Measurements in millimeters: Body, 23.0; pronotum, 4.7; front 

 femur, 3.2; hind femur, 13.0; tegmen, 18.0. Greatest width of 

 pronotum, 4.2; of hind femur, 3.2. 



Variation: The size of 10 representative males measured (in milli- 

 meters) varies in pronotal length from 3.5 to 5.0 (av. 4.4), in length 

 of hind femur from 10.0 to 14.0 (av. 12.0), and in length of tegmen 

 from 15.5 to 21.8 (av. 18.3). Six measured females vary in pronotal 

 length from 4.2 to 5.3 (av. 4.7), in length of hind femur from 11.5 to 

 14.0 (av. 12.8), and in length of tegmen from 16.5 to 23.5 (av. 18.5). 

 Western specimens average larger than eastern ones. In most speci- 

 mens the tegmen extends about 2 to 3 mm. beyond the apex of the 

 hind femur, but in some it scarcely exceeds it by as much as 5 mm. 

 The male cercus usually is essentially like that of the holotype, but 

 the tiny apicoventral "tooth" frequently is absent, and general shape 

 is somewhat variable (fig. 7,d-2,dA). Very little variation in the 

 shape of the epiphallus has been noted. 



Intergradation is shown by the shape of the dorsal valve of the 

 aedeagus; in intermediate specimens the ventroanterior margin of the 

 dorsal valve varies between the clearly excavate one of bilituratus 

 vultumus and the simply recurved margin of bilituratus bilituratus. 

 Wet preparations often show membranous folds apically ("m" of 

 fig. 3,c). Some intergrading specimens represent one of the two sub- 

 species more strongly; others represent the other one, and some are 

 fully intermediate. In some cases, as is true of material from Erie 

 and Wood Counties, Ohio, and from Lafayette, Ind., fairly large 

 series of males taken at the same time and place vary. This situation 

 suggests that a mingling of genes of the two subspecies is occurring 

 and that the populations are intergrading, though certain individuals 

 appear nearly typical of one subspecies. 



A specimen collected at Muscatine, Iowa, Sept. 12, 1935, by R. L. 

 King probably is bilituratus vultumus, but the dorsal valve (fig. 2,m) 

 is very unusual, recalling certain very long-winged Arizona specimens 

 of bilituratus defectus. The specimen is very long-winged, the tegmen 

 27 mm. long and extending 11.5 mm. posterior to the hind femur. 

 In 1935 Iowa was experiencing a buildup of grasshoppers, but there 

 is no record of extensive flights into the State then, though at other 



