Otter 
189 
B. Toes short, partially webbed; claws short, curved, and often 
semi-retractile (Mustelines) . 
a. Form slender; digitigrade. 
a.'. Premolars 3 above and below. 
a". Toes not webbed, soles hairy. Putorius, p. 192 
b". Toes webbed, soles naked. Lutreola, p. 198 
b'. Premolars 4 above and below; tail long and bushy, more 
than \ total length. Mustela, p. 200 
b. Form stout; plantigrade; tail less than I total length, bushy; 
4 premolars above and below. < Gulo, p. 203 
C. Toes long and straight, not webbed; claws straight or very 
slightly curved, those of fore feet elongated (Melince). 
a. Body elongated, form more slender than in b; tail well over 
i total length and bushy, 
a'. Color pattern with four interrupted white lateral stripes 
on black ground. Spilogale, p. 212 
b'. Color pattern two white lateral stripes on black. 
Mephitis, p. 208 
b. Form stout; tail short, less than I total length; no special 
color pattern. Taxidea, p. 205 
Subfamily LUTRINiE 
Carnivora of aquatic habits with short, broad, and depressed 
heads; small ears; short and rounded feet, with the toes 
webbed and the claws small, curved, and blunt; kidneys 
conglomerate. 
Genus LUTRA (Lat., an otter) 
Lutra Brisson, Regn. Anim., 2d. ed., p. 201 (1762). Type Mustela 
Ultra Linnaeus. 
Revision, Rhoads, Trans. Amer. Philos. Soc, N. S., xix., pp. 
417-439 (1898). 
Body long and slender; tail long; legs short; soles and palms 
hairy; outline of skull above flat- rostrum short; postorbitals well 
developed; a pronounced postorbital constriction; hinder portion of 
skull wide; dentition: i. f ; c. |-; pm. |;m.| X 2 = 36; upper molar 
large, quadrate; first upper premolar very small; upper carnassial 
with tricuspid blade and large inner lobe. 
The members of this genus are of exclusively aquatic 
habits, living principally if not entirely on fish which they 
catch by diving and swimming. It is practically a cosmo- 
