XXIV. 



Bog-lemming, Lemming-vole, Lemming-mouse, Bob- 

 tailed Meadow-mouse or Bog-mouse. 



Synaptomys horealis (Richardson). 



(Gr. synaptis, joined together; mys, mouse, because it joins the Meadow-mice with the 

 Lemmings; L. borealis, of the north. 



Arvicola borealis RiCHARDSON, 1 828, Zool. Journ., Ill, No. 



12, 1828, p. 517. 

 Synaptomys horealis Preble, 1908, N. A. Fauna, No. 27, p. 183. 



Type Locality. — Ft. Franklin, Great Bear Lake. 



The genus Synaptomys (Baird, 1857) comprises Field- 

 mice which look much like the ordinary Field-mice (Microtus), 

 because both are on such a small scale, but if they were enlarged 

 to the size of a Deer, we should find them as different as Caribou 

 and Elk. Aside from the very different skulls and other 

 points which require dissection to show, the Lemming-mouse 

 has the coarse brown coat, the grooved upper incisors^ and a 

 little bob tail sticking barely half an inch beyond the fur, while 

 the Vole has a fine brown coat, smooth teeth, and tail over an 

 inch beyond the fur. 



They have the same tooth formula, but the teeth them- 

 selves present many differences of detail. 



SIZE In addition to the generic characters, this Bog-lemming 



has: Length, 5I inches (130 mm); tail, i inch (25 mm.); 

 hind-foot, | inch (18 mm.). 



COLOUR In colour and outward appearance this animal is some- 



what like Microtus drummondi, but it is much redder above 

 and darker below, without white; the feet are dark brown; it 

 has a chestnut spot under the ear. A Fort Franklin male 

 specimen' before me has on each hip a white tuft of hair that 



* No. 133,905, U. S. Biological Survey Coll. 



558 



