96 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 

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

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

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

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

 Henderson from Goodrich, near Crow Creek, June 22, 191 2; from Foston, June 

 25, 191 2; from ten miles north of Sterling, July 23, 191 2. 



Genus TROPIDONOTUS Kuhl 



Tropidonotus 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. 



