90 UNIVERSITY OF COLORADO STUDIES 



eighth to one-fourth of the total length; average specimens under 

 three feet; body stout and heavy. 



Ground color grayish, to grayish yellow or grayish brown; ventral 

 parts whitish, mottled with irregular dark blotches and with a wide 

 dark area down the center; dorsal pattern of a central row of large, 

 rather rounded, brownish or blackish spots, separated by spaces of 

 about the same size of the ground color; the sides with two rows of 

 dark spots smaller in size, placed one above the other opposite the 

 spaces between the dorsal spots; another set of more suffuse spots 

 showing rather indistinctly between the successive pairs of lateral 

 spots; under parts of the head whitish; top of the head with a narrow 

 light stripe crossing it in the region of the eyes; a dark, oblique band 

 extending from the posterior portion of the supraocular plate to the 

 posterior angle of the mouth, including all or part of the last two 

 superior labials; a second, larger, oblique band, just back of, and 

 separated by a single row of scales from the first dark band. 



Range, Montana and Dakota south into Mexico, east to Arkansas. 

 A plains species. 



Colorado specimens. — University Museum: La Junta, July, 1905 (425 mm.), 

 G. S. Dodds, No. 247; Hudson, August, 1905 (255 mm.), H. Markman, No. 248; 

 five miles east of Grover, June 26, 1906 (170 mm.), J. Henderson, No. 249; Lodge- 

 pole Creek, near Ovid, July 17, 1912 (190mm.), J. Henderson, No. 250; near 

 Julesburg, July 17, 1912 (525 mm.), J. Henderson and M. M. Ellis, No. 251; 

 three miles east of Osgood, June 22, 1912 (550 mm.), J. Henderson, No. 252; 

 Colorado Slate Historical and Natural History Museum: Denver, August 13, 1902 

 (460 mm.), C. Murray; Denver, June 2, 1903 (430 mm.), H. G. Smith; Lamar, 

 June 20, 1904 (790 mm.), H. G. Smith; Lamar, June 8, 1904 (750 mm.), H. G. 

 Smith; Denver, June 1, 1905 (480 mm.), E. Bethel; Agricultural College Museum: 

 Ft. Collins, July, 1892 (2 specimens, 220 and 310 mm.), C. F. Baker; Stale 

 Teachers' College Museum: Greeley and Trinidad, A. E. Beardsley; reported by 

 Henderson from Goodrich, near Crow Creek, June 22, 1912; from Foston, June 

 25, 1912; from ten miles north of Sterling, July 23, 1912. 



Genus TROPIDONOTUS Kuhl 

 Tropidonolus Kuhl, Isis von Oken, p. 205, 1826. 

 Natrix Laurenti, Synopsis Reptilium, p. 73, 1768. 



Anal plate divided; scales keeled, in 17 to 23 rows; posterior 

 maxillary teeth longer than those in front; rather large snakes. 



