CHARACTERS OF SOME SPECIES OF LUTRINiE. 537 



jawed form, the plane of the rhinarium is ahiiost vertical. 

 Otherwise it closely resembles that of the European species, 

 except that its upper edge is straight transversely between the 

 posterior edges of the nostrils and its inferior edge less produced. 



So far as it is possible to judge on the dried skin, the rhinarium 

 of the African clawless Otter {Aonyx capensis) resembles that of 

 the Indian form L. cinerea, which is often associated with it. 



The other well-known African Otter [Luira inaculicoUis) has a 

 very different rhinarium, although as in L. cinerea its plane is 

 vertical. It is very much reduced in size, being overgrown with 

 hair to such an extent that little more than the edges of the 

 nostrils a.re naked. The inferior border is quite straight and the 

 infranarial portion on each side is shallow, while its upper edge 

 is sinuously concave backwards, owing to the advancement of the 

 hair in a curved line on each side from the posterior margin of 

 the nostril to the middle line, where it nearly divides the rhinarium 

 into two portions. From this it results that the middle of the 

 rhinarium is less than one-fourth of the depth of the upper lip. 



The Facial Vibrissce. — The facial vibrissse in Otters are, as a 

 rule, exceedingly coarse and numerous as in most predatory 

 aquatic mammals. Two points to be noted, however, are that 

 the mystacials, as compared with those of normal terrestrial 

 mammals, are relatively short, not longer that is to say than 

 the genals, and that the genal tufts, especially the inferior, are 

 exceptionally well developed, the vibrisspe being numerous and 

 long. The material examined does not warrant the opinion that 

 Lutra lutra, L. cinerea, and L. inaculicollis differ in any way 

 vv^ith respect to their vibrissse ; but the vibrissae of Aonyx capensis 

 are decidedly less stout and stiff, especially perhaps those forming 

 the upper genal tuft *. 



The Ear. — The external ear in Otters is always small and oval, 

 and comparatively simple in structure, the bursa being absent. 

 In the European species {Lutra liotra) the tragus and antitragus 

 are tolerably well developed, with a well-marked notch between 

 them, and just inside the antitragus there is a strong ridge-like 

 thickening forming the posterior rim of the cavi^y. The supi-a- 

 tragus is a shelf-like ridge with well-developed fleshy lobe. 



In the Indian small-clawed Otter [L. cinerea) the ear is very 

 like that of L. lutra, but relatively smaller, the cavity not 

 extending so high above the supratragus ; and the tragus and 

 antitragus are inconspicuous. On the dried skin I could find 

 nothing distinctive about the ear of Aonyx capensis. In L. macu- 

 licollis the ear is simpler than in L. cinerea. The inferior edge of 

 the cavity shows no trace of a notch, the tragal and antitragal 

 thickenings being altogether suppressed, and the supratragus is 

 represented merely by a rounded tubercle corresponding to the 

 fleshy lobe of this thickening seen in L. lutra and cinerea. 



* Hinton (Ann. Mag. Nat. Hist. (9) vii. p. 195, 1921) has recently proposed the 

 new generic name Faraony.r for two clawless Otters from the Congo which differ, 

 amongst other things, from Aonyx in the. complete suppression of the superciliary and 

 upper genal tufts. 



