35. Skull almost flat in upper profile; four or five lower cheek teeth; last 



two upper cheek teeth as wide as, or wider than, long 36. 



Skull somewhat convex in upper profile; six lower cheek teeth; next to 



last upper cheek tooth definitely longer than wide 37. 



36. Six lower incisors; skull about four inches long, greatest width less than 



2/3 the length 



Lutra Otter 

 Four lower incisors; skull about five inches long, greatest width 2/3 the 

 length; West Coast; rare 



Enhydra Sea Otter 



37. Palate reaching one-third of the distance between last molar and bulla; 



narrowest part of skull just behind orbits 

 Maries Marten and Fisher 

 Palate reaching half way between last molar and bulla; narrowest part 

 of skull middle of temporal fossa 

 Gulo Wolverine 



38. Skull almost flat on top; palate extending well beyond the back of last 



molars 39. 



Skull highest in frontal region; palate ending in line with, or slightly 



behind, back of last molars 40. 



39. Bulla flattened; ante-orbital opening scarcely visible from dorsal view; 



skull about two and one-half inches long; zygomatic bar heaviest an- 

 teriorly 



Mustela vison Mink 

 Bulla rounded; ante-orbital opening plainly visible from dorsal view; 

 skull usually less than two inches long; 2;ygomatic bar weakest an- 

 teriorly 



Mustek Weasels 



40. Bulla well rounded; next to last upper molar elongate-oval 



Spilogale Spotted Skunk 

 Bulla flattened; next to last upper molar triangular 4L 



41. Palate ending at level of back of last molars; four upper cheek teeth 



on each side, the first very small 

 Mephitis Common Skunk 

 Palate extending almost as far behind the level of the back of last molars 

 as the length of those teeth; three upper cheek teeth 

 Conepatus Hog-nosed Skunk 



42. Teeth chestnut-colored; no 2,ygomatic bar 43. 

 Teeth not reddish; a fragile bar present 44. 



43. Teeth behind the large incisor with first and second large and of almost 



equal size, third and fourth much smaller and about equal, fifth minute 

 Blarina Short-tailed Shrew 

 The third tooth (as counted above) not much smaller than the second 

 Sorex Long-tailed Shrew 



44. Premaxilla without palatal or ascending processes, leaving a gap in the 



front of the upper jaw, or with only two incisors between the much 



longer canines 45. 



No such gap; front pair of teeth larger than the next three or four 54. 



528 



