A Key to the Genera of North American Mammals 
JJ. Arboreal species, tail long and bushy. 
ScruRus, 168-176 
DD. Tooth row nearly continuous, leaving no large gap at the side 
of the jaw. 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 3, c }, p 4, m 8. 
CONDYLURA, 190 
GG._ No fleshy star on the nose. 
._ Tail naked; teeth,i$,cj, p $3,m4....ScaLops, 188 
HH. Tail hairy; teeth, i #c 1,p#,m3 . PARASCALOPS, 189 
FF. Fore feet normal. 
G. Pete short 1-4 the head and body; teeth, i #—3, c}, p 2, 
TTS 4 niches ainactigs Wee ee teadiee teae Cee BLARINA, 130-183 
GG. Tail at least 1-2 the head and body; teeth, i #, c }, 
Ped Oy oss kee eee Sorex, 184-187 
EE. Size medium or large; eyes well developed. 
F. Toes webbed. 
G. Hind feet large and very different from the front ones, 
resembling flippers; teeth, i$,ci,p3 sm 3, LATAX, 223 
GG. Feet all alike; teeth, i $,c +, p $,m }..LuTRA, 219-223 
FF. Toes not webbed.: 
G. Toes, five on all feet. 
H. Teeth, 14,¢+, Px, ms. 
I. Nose produced into a slender snout; tail obscurely - 
PINTO cara tishace tyne seen Seen eee NASUA, 254 
II. Nose not lengthened; tail strongly ringed with 
black and white. 
J. Body thick-set; feet plantigrade. Procyon, 247 
JJ. Body slender, weasel-like; feet only partially 
plantigrade seteneaee eo atere rae BASSARISCUS, 254 
HH. Teeth,i$,ct+, p4,m}. 
I. Body heavy, bear-like; feet slightly plantigrade. 
GULO, 245 
II. Body more slender; feet digitigrade. 
MUSTELA, 241-245 
HHH. Teeth, i}, cH, p $—§, m, 
I. Claws long 3 and conspicuous; ae black and white. 
White in two long stripes..MEPHITIS, 224-229 
J. Markings more complicated . _SPILOGALE, "230 
Claws very long and conspicuous; color gray. 
TAXIDEA, 230 
III. Claws short; color brown (often white in winter). 
PUTORIUS, 231-240 
HHHH. Teeth, i 3,ci, p $,m3; size very large (Bears). 
I. Color white.:..s.0h THALARCTOS, 255 
II. Color, black, brown or tawny....Ursus, 257-264 
GG. Toes, five in front and four behind. 
ar Toes not retractile; teeth, i $,c +, p $,m 
3° 
ees incisors lobed aaa ah ne he CANIS, 277-283 
pper incisors not lobed. 
Tail with soft under fur...... VULPES, 264-275 
}, Tail coarse’: (4.05'.5.008 «es Urocyon, 275-277 
HH. oes retractile. 
I. Tail very short (4-6 ins.); teeth, i 3, c 3, p 3, m#. 
Lynx, 284-288 
II. Tail long, equal to more than half the head and 
body; teeth, i $,c j, p 3, m+}... FELIs, 288-293 
300 

