1907] Additions to the Geological Survey Museum. 177 



NOTES ON TWO RECENT ADDITIONS TO THE ZO- 

 OLOGICAL COLLECTIONS IN THE MUSEUM OF 

 THE GEOLOGICAL SURVEY OF CANADA. 



By J. F. Whiteaves. 



The additions are two specimens that were presented by 

 the Rev. J. H. Keen, of Metlakatla, B.C., per Dr. James 

 Fletcher, on the 24th of December, 1907. Thev are as follows: 



(1). MiCROTUs M.vcRURUs, Merriam. 



{The Olympic Vole). 



"Parturiunt montcs, nascitur ridiculus mus." 



Skin of a female of this species. The animal was captured 

 by Mr. Keen at or near Metlakatla, on the 28th of August, 1907. 



Under the auspices of the U.S. Department of Agriculture, 

 Mr. Vernon Bailey has published a "Revision of American 

 Voles of the Genus Microtus'' in 1900, and Mr. David E. Lantz, 

 "An Economic Study of Field Mice (Genus Microtus)" in 1907. 



" Field mice, of the genus Microtus," writes Mr. 

 Lantz, have "stout bodies, blunt, rounded muzzles, small eyes, 

 and short ears often completely concealed in the fur. The 

 tail is short and hairy ; the soles of the feet are naked or clothed 

 with short hairs, and have five or six foot pads (plantar ttibercles). 

 The incisors are broad and not grooved. 



"The molar teeth, in all members of the genus, like the 

 incisors of all rodents, grow continuouslv throughout the life 

 of the animal and do not develop roots. They are prismatic 

 in form, and the crowns show triangular dentinal spaces sur- 

 rounded by lines of harder enamel. These curious enamel 

 patterns are of great importance in the classification of the 

 animals, as they are but slightly affected by age and wear and 

 are remarkably constant for each species. 



"About 165 living species and subspecies of Microtus have 

 been recognized (1904), of which about 78 are North American." 



And of these 78, it may be added, about 30 are now known 

 to occur in Canada. In the Museum of the Survey there are 

 about 100 skins of Canadian voles or field mice of this genus, 

 representing at least 10 species or subspecies, and including a 

 fine series of skins of M. Drummondii from Alberta and British 

 Columbia. 



