M*CHESNEY ON DAKOTA MAMMALS. 



215 



face of the pouch, and along the superior and inferior borders thereof, its 

 fibres expanding so as to cover nearly the entire under surface of the sac. 

 The fibres running along the superior border of the pouch are attached 

 with those of the muscle passing over the upper part of the pouch to 

 the superior maxillary bone. The remainder of the fibres are attached 

 to the outer and lower surface of the body of the inferior maxillary bone, 

 precisely similar to the attachment of the platysma myoides. The mus- 

 cle in this portion of its course is covered by the sac, and is in relation 

 below, with the muscles of the inferior maxillary bone and of the neck. 

 It will thus be seen that the great muscular power possessed by the 

 animal over its pouch is exerted from its lower or inner surface, its 

 upper or outer surface being but poorly supplied with muscular fibres. 



Thomomys talpoides, {Bicli.) Baird. 



This Gopher is not abundant in this region. It shares many of the 

 habits of its relative, G. bur sarins, and is found occupying the same 

 ground and apparently living in the midst of that species. 



This Gopher breeds during the latter part of July and early in August, 

 and I believe there is but one litter annually. 



Measurements of specimens taken are as follows : — 



Place of col- 

 lecting. 



Fort Wads- 

 worth, Dak. 



..-.do 



.-..do 



....di 



Fort Sisseton, 

 Dak. 



Date of col- 

 lecting. 



May 14, 1876 



May 15, 1876 

 July 28, 1876 

 Aug. 16, 1876 

 May 25, 1877 



SCIUEID^. 



Tamias STRIATUS, (Linn.) Baird. 



The beautiful little Chipmunk is quite common in this vicinity, and 

 makes his appearance about the first of April, thus being one of the 

 earliest of our mammals to welcome the return of spring. 



The Chipmunk disappears by the end of April, and I have been un- 

 able to learn anything of its breeding. 



A large number of specimens have been captured, but I was unfor- 

 tunately unable to preserve them at the time. 



