ON THE EXTERNAL CHAllAGTERS OF LUTKlNiE. 535 



29. On the External Characters o£ some Species o£ Lutrinaj 

 (Otters). By R. I. PococK, FJi.S., F.Z.S. 



[Keceived April 19, 1921 : Read May 24, 1921.J 



(Text-figures 19-21.) 



Contents. 



Page 



The Rhiiiarium 535 



The Facial Vibrissse 537 



The Ear 537 



The Feet 539 



The Alius and External Geiiitalia 542 



The Genera of Otters of the Old World 542 



The Descent of the Lutrinae 544 



Since the different species of Otters are remarkably alike in 

 general appearance, and the published notes on their external 

 characters, to which Gray in particular paid great attention more 

 than half a century ago, were taken apparently from dried skins, 

 tlie following illustrated descriptions of tbe three species, Luira 

 lutra^ L. maculicollis, and L. cinerea^ exhibited dui'ing the past 

 few years in the Zoological Gardens, supplemented by an 

 examination of the softened skin of a stuffed example of Aonyx 

 capensis, and followed by some general conclusions with regard to 

 the systematic status of the species examined and the descent of 

 the Lutrinse, may prove of interest. 



The Ehmariuni. — The extent to which the rhinarium is covered 

 with hair has frequently been used since Gray's time as one of 

 the best external characters for distinguishing the species of 

 Otters. 



In Lutra lutra it is entirely naked and a little Avider than 

 long ; but judging from descriptions is variable in shape. Gray, 

 for example, described the lower edges as straight and the upper 

 as " rather produced and angular." Blanford corroborates this, 

 saying that the " upper edge is not straight but projects in the 

 middle and is concave on each side, running up considerably to 

 the hinder edge of the nostril." Miller, on the contrary, says the 

 upper margin is " strongly convex at middle, the lower slightly 

 so." In the specimen here figured the upper edge agrees precisely 

 with Blanford's description, and the lower margin is angularly 

 produced. The nostrils are widely separated and there is no 

 philtrum, the upper lip being continuously hairy and about as 

 deep as the height of the rhinarium. This species has a com- 

 paratively long muzzle, as shown by the skull, and the plane of 

 the rhinarium is inclined upwards and forwards at an angle of 

 about 60° or less. 



In the Asiatic small-clawed Otter {Lutra cinerea), a short- 



