STRIPED SPE RMOPHILE. 



31 



STRIPED PRAIRIE SPERMOPHILE. 



Spermophilus tridecemlineatus (Mitcliill). 



[Plate I— Map 1.] 



Description— This is the slenderest of the spermophiles, with ears about an eighth 

 of an inch long; the tail is about half as long as the head and body, flattened and 

 slightly bushy. The belly and lower sides, including legs, feet, throat, nose, and 

 lower half of cheeks, are dull buff or ashy buff; the back is striped with six narrow 

 buff colored lines and seven wider lines of dark brown, each brown line inclosing a 

 row of small spots. Along the middle of the back the stripes extend from the top of 

 the head to the tail, becoming shorter on the sides.* Specimens inhabiting the arid 

 plains are considerably paler than those from the prairies of the Mississippi Valley 

 proper, and have been separated as a subspecies under the name Spermophilus tride- 

 cemlineatus pallidiis. 



The following measurements were taken from a specimen selected from fifteen 

 adults as representing the average size: Total length from end of nose to tip of tail 

 vertebrae, 252 millimeters (10 inches) ; length of tail (turned at right angles to back 

 and measured with dividers from angle at base to tip of vertebrae) 88 millimeters 

 (3£ inches) ; length of hind foot from point of heel to tip of longest claw, 33 millime- 

 ters (1J inches). • 



Range. — This well-known little animal is widely distributed through- 

 out the central part of North America, ranging continuously from east- 

 ern Michigan to Montana and Colorado, and from central Texas north to 

 the plains of the Saskatchewan in Canada, where it reaches latitude 

 53o N. 



Its range embraces all of the five States of North and South Dakota, 

 Iowa, Nebraska and Kansas, and practically all of the Territory of 

 Oklahoma. North of the United States recent observations have failed 

 to carry it beyond Carlton House, Saskatchewan, where it was found 

 more than sixty years ago. Its eastern limit may be indicated by a 

 line following the Eed Kiver valley southward to Pembina, N. Dak., 

 and then running diagonally across Minnesota through Crookston, 

 Park Eapids, and Fort Ripley, to the Wisconsin border near Pine City. 

 Wisconsin records are mainly confined to the southeastern part 

 of the State, although it has been found at Sparta and reported 

 as far north as Ripon. In Michigan the northernmost records are 

 Big Rapids, Byers, Palo, and Matherton. Spermophilus tridecemlinea- 

 tus barely enters Ohio and is restricted to the northwestern part of 

 Indiana, not passing east of the Wabash River according to Mr. 

 F. C. Test. The most southern point in Illinois from which it has 

 been reported is Belle Prairie. Harrisville and Golden, Mo., and 

 Ardmore, Ind. Ter., are near its southeastern limits, while Point, 

 Meridian, Clyde, and Epworth, Tex., mark the southern limits of its 



* An animal frequently confused with this species is the chipmunk (Tamias stria- 

 tus), which has the middle of the back striped with black, buff, and brown, but no 

 spots, and is further distinguished by a more bushy tail and longer ears. It is a for- 

 est animal and climbs trees, while the Striped Spermophile belongs to the prairies 

 and does not climb trees. 



