168 BULLETIN (51, UNITED STATES NATIONAL MUSEUM. 



Forks, Fish Creek, Montana; Peabody, Onaga, Fort Riley, Fort 

 Harker, Kansas; Platte River, Fort Kearney, Nebraska; Ames, Des 

 Moines, Palo Alto County, Clay County, Woodbury County, Iowa. 



Further collecting will extend the range somewhat beyond the 

 extreme points listed above, to the north, south, and east. At pres- 

 ent the most debatable territory is to the south and east, for here 

 parietalis meets two allied forms (eques and sirtalis), which it resembles 

 so closely that it is impossible to distinguish preserved specimens 

 with certainty. This is true of specimens from northern New Mexico 

 and Arizona, and Minnesota, eastern Iowa, and western Illinois. 

 The points of resemblance between these forms will be discussed under 

 "variation," but it should be stated here that no reliance can be 

 placed upon the published lists which record parietalis for any of the 

 last named States. Thus, Cope records it from Lake Valley, New 

 Mexico, but the basis of the record proves on examination to be a 

 specimen of eques, while apparently several of his dorsalis specimens 

 from the same state, as well as Garman's Illinois specimens and 

 Ruthven's Isle Royale specimens (1906, 111-112), are not at all 

 typical and are mostly to be considered ''intermediate." At the 

 present time the eastern limit of typical parietalis may be given very 

 generally as the "prairie peninsula" in central and southeastern 

 Minnesota, eastern Iowa, and northeastern Missouri. The southern 

 limit in central United States can not even be approximated, although 

 it doubtless lies in the northern part of Texas, Arizona, and New 

 Mexico. The southernmost point from which we have examined 

 specimens from California is Fresno, but Van Denburgh (1897, 203) 

 records it from "San Bernardino (Ontario) and Riverside (Riverside) 

 counties," and Grinnell (1907, 49) from the Pacific slope of Los 

 Angeles County. The known range has been platted- on the map 

 (fig. 73). 



Variation. — Like its relatives, eques and sirtalis, parietalis is little 

 variable in scutellation. Large series alone, therefore, will reveal 

 geographic differences if they exist. Unfortunately, while I have 

 examined about three hundred and fifty specimens, these have been 

 from many localities, so that single regions are represented only by 

 small numbers. On the other hand, in view of the constancy of the 

 characters, geographic variations must be very slight, and I believe 

 that the data accumulated is quite representative of the actual con- 

 ditions. In every specimen in which they were counted (311) the 

 dorsal scale formula is 19-17. In regard to the labials, the suites 

 are all alike in that most of the specimens have the labial formula 

 7/10, but quite frequently S supralabials and 9 or 11 infralabials. I 

 have seen but four specimens in which the variation exceeded tliis 

 amount, one from Eureka, California (Field Museum, 1111), and 

 three from Pullman, Washington (Ruthven collection), each of which 



