A Key to the Genera of North American Mammals 



JJ. Arboreal species, tail long and bushy. 



SCIURUS, 168-176 

 DD. Tooth row nearly continuous, leaving no large gap at the side 



of the iaw. Incisors small and always more than two. 

 E. Size small (less than seven inches long) , fur always drab or 



iron gray, soft and silky; eyes rudimentary. 

 F. Fore feet flattened for digging (Moles). 



G. A fleshy star on the nose; teeth, i , c } , p |, m i| . 



COXDYLURA, 190 

 GG. No fleshy star on the nose. 



H. Tail naked; teeth, i !|, c /,, p %, m f . . . .ScALOPS, 188 

 HH. Tail hairy; teeth, i ?, c }, p -], m ;J. PARASCALOPS, 189 

 FF. Fore feet normal. 



G. Tail short 1-4 the head and body; teeth, i ^ ?i, c /,, p f, 



m f BLARINA, 180-183 



GG. Tail at least 1-2 the head and body; teeth, i :?, c J, 



p f, m f '. SOREX, 184-187 



EE. Size medium or large; eyes well developed. 

 F. Toes webbed. 



G. Hind feet large and very different from the front ones, 

 resembling flippers; teeth, i ?,, c {-, p }, m i, LATAX, 223 

 GG. Feet all alike; teeth, i f , c {, p f , m -}-. . LUTRA, 219-223 

 FF. Toes not webbed.' 

 G. Toes, five on all feet. 



H. Teeth, i f , c j, p f , m 3. 



I. Nose produced into a slender snout; tail obscurely 



ringed NASUA, 254 



II. Nose not lengthened; tail strongly ringed with 



black and white. 



J. Body thick-set; feet plantigrade. PROCYON, 247 

 JJ. Body slender, weasel-like; feet only partially 



plantigrade BASSARISCUS, 254 



HH. Teeth, i f , c I, p -}, m \. 



I. Body heavy, bear-like; feet slightly plantigrade. 



GULO, 245 



II. Body more slender; feet digitigrade. 



MCSTELA, 241-245 

 HHH. Teeth, i f, c i, p f-7-f, m, $. 



I. Chiws longand conspicuous; colors black and white. 

 J. White in two long stripes. . MEPHITIS, 224-229 

 JJ. Markings more complicated. . SPILOGALE, 230 



II. Claws very long and conspicuotis; color gray. 



TAXIDEA, 230 



III. Claws short; color brown (often white in winter). 



PUTORIUS, 231-240 

 HIIHH. Teeth, i !{, c }-, p :}-, m -j ; size very large (Bears). 



I. Color white THALARCTOS, 255 



II. Color, black, brown or tawny. . . .URSUS, 257-264 

 GG. Toes, live in front and four behind. 



H. Toes not retractile; teeth, i ; ; , c J. p j. m -.. 



I. Upper incisors lobcd CANIS, 277-283 



II. Upper incisors not lobed. 



J. Tail with soft under fur VULPES, 264-275 



JJ. T.iil coarse UROCYON, 275-277 



HIT. Toes retractile. 



I. Tail very short (4-6 ins.); teelli, i '. c- ]. p -.. m ]. 



' LYNX, 284-288 



II. Tail long, ennui t> m<>n- 1h;m half tin- head and 



body; teeth, i f , c |, p |, m } . . FEUS, 288-293 



300 



