CHAHACTERS OF SOME SPECIES OF LUTRINiE. 539 



The Feet *. — The feet of the Lutrinse or Otters are so vari- 

 able that it is hardly possible to mention a single character in 

 which they differ from those of the other Mustelidae collectively, 

 except that the fore paw is always much smaller than the hind. 

 In some cases the digits are less fully webbed than in any other 

 genus of the family except Lyncodoyi ; but in the typical forms 

 the feet are more fully webbed because the digits are relatively 

 longer and more widely separable, owing to the greater width 

 and less emargination of the webs, especially of those joining the 

 first and second, second and third, and fourth and fifth digits. 



In Lu.tra lutra, for example, the third and fourth digits of the 

 fore foot are not more widely separated nor more fully webbed 

 than in Charronia or Gulo ; but the webs between the fourth 

 and fifth, and third and second, and second and first digits extend 

 with a nearly straight edge between points near the middle of 

 the margins of the digital pads. The claws are well developed 

 and project well beyond the tips of the digital pads, and the sole 

 of the foot is naked back to the proximal margin of the single 

 lai-ge, sometimes nearly hemispherical, sometimes transversely 

 elongated carpal pad. The radial or internal element of the 

 carpal pad is not sepai'ately distinguishable. There is a short, 

 naked area between the carpal and the plantar pad ; and the 

 main part of the Is^^ter is well developed but narrow, that is to 

 say about as wide as long, and distinctly three-lobed ; the two 

 lateral lobes nearly meet behind the median, and the pollical 

 element is small" anj indistinctly defined from the posterior end 

 of the adjoining lobe. The hair of the wrist extends right down 

 to the carpal pad. Tl''^ hind foot is markedly larger than the 

 fore foot owing to the greater elongation of the digits, which 

 have consequently deeper aiid widej; webs. The plantar pad is 

 remarkably modified. ' Its median lobe is elongated and some- 

 what heart-shaped ; the, external lube, defined by a deep groove, 

 extends far back l)ehind the median- in contact thi'oughout its 

 length with the inner lobe, which is almost as long but has its 

 free edge emarginate, the proximal or pollical element being 

 large. The three main lobes just described are defined from 

 each other by a Y-shaped groove. The hair of the metatarsus 

 extends down to the proximal end of the plantar pad, and thei^e 

 is no trace of metatarsal p.ad. 



In Lutra maculicollis the digits are relatively longer than in 

 L. lutra and the webs are better developed, extending to the 

 distal end of the digital pads on their inner sides. The plantar 

 pad of the fore foot is more norpnally shaped, being considerably 

 wider than long and four-lobed. . The median lobe is not narrowed 

 behind, the posterior ends of the main lateral lobes are widely 

 separated, alid the pollical lobe is clearly defined. The single 

 ulnar carpal pad is much smaller than in L. lutra ; and apart 

 from the pads which are naked, the underside of the foot is 

 covered with fine, short scattered hairs. The hind foot differs 

 * The carpal vibrissse are present in all tlie specimens described. 



