542 MR. E. I. POCOCK ON THE EXTERNAL 



A fui-tlier stage in the disappearance of the webs is shown in 

 Paraonyx, which is described by Hinton as having unwebbed 

 digits on the fore foot and the digits of the hind foot webbed 

 to the base of .tlie second phalange, apparently as in the fore 

 foot of A onyx. 



Anus and External Genitalia. — About the anus and external 

 genitalia there is very little to be said, since they closely resemble 

 those of such typical Mustelidfe as Martes in having the anus 

 encircled and the perinseum covered with hair and the two normal 

 anal glands present, with the scent of the secretion compara- 

 tively inoffensive. The penis of Lutra lutra is moderately long, 

 and is supported by a stout, nearly straight baculum* about 

 60 mm. long, convex above, flatter and sometimes faintly grooved 

 below, and gradually narrowed from the base up to the apex, 

 where it expands into two short, deeply cleft, thick condyle-like 

 bi-anches, curved downwards. The branches are not alike, the 

 right being a little thinner and less curved than the left. The 

 urethra runs along the underside of the baculum, which is in- 

 vested in soft vascular distensible tissue, and opens in the middle 

 line below, just behind the condyle-like thickenings of the 

 baculum . 



The baculum of L. cinerea is very like that of L. lutra, but is 

 of more even width throughout and the two terminal branches 

 are not curved downwards. 



The Genera of Otters of the Old World. 



Apart from the incidental mention of Paraonyx, the Otters 

 discussed in the foregoing pages have been refeired to the two 

 genera, Lutra and Aonyx. But if the nomenclature of this group 

 is to be brought into line with that of other groups of Mammals, 

 as the publication of Paraonyx seems to demand, it is certain 

 that several generic and subgeneric terms long ago proposed but 

 never as yet adopted will have to be restored to use. I have 

 neither the material nor the time to go into the quesfion beyond 

 the limits of the species exhibited in the Zoological Gardens, of 

 which skulls or skins, or botli, are in the Society's possession. 



Otters unfortunately, although so widely distributed, are very 

 seldom in the live animal market, and it does not a.ppear that 

 more than the following species have been exhibited in the 

 Gardens : — Lutra lutra, Z. harang (entered as oiair), L. cinerea, 

 L. macidicollis, and L. platensis. 



Each of the four exotic species has been severed fiom Lutra, 

 and received a generic or subgeneric name. About platensis, 

 named Nutria by Gray, I have nothing to say, the specimen 

 having been sent unexamined to the British Museum. The 

 Oriental species determined by Thomas as harang was referred 

 by Gray to the subgenus Lutrogale under the name monticola. 

 1 have no personal knowledge of the external characters ; but the 



* Described by Blainville, Pohl, and other autliors. 



