546 ON THE EXTERNAL OHAEACTEES OF LUTRlNiE. 



the Otters niid the Seals may be explained in this way. Otters 

 masticate their fish and require broad, ilat-crowned teeth for the 

 purpose. Seals swallow them entire, and the teeth are modified 

 for catching and holding the slippery prey. 



[Note.] After this paper was written, Mr. Thomas drew my 

 attention to the elaborate monogrnph of the Lutrinse published 

 by Pohle in November 1920 (Arch. f. Naturg. 1919, pt. 9, pp. 1- 

 247). So far as the species I have discussed are concerned, Pohle's 

 systematic results, based upon skulls, teeth, and dried skins, differ 

 m two points only from mine. While admitting the genera 

 Amhlony.v and Aonyx* as distinct from Lutra, he granted Zwitro- 

 gale harang only subgeneric rank under Litira, and dismissed 

 maculicollis and two related species as "Die macuUcollis-Gvw^^e^^ 

 of Lutra f. Since the properly constituted subgenera and 

 "groups" of species of one generation of workers almost 

 invariably become the genera of the next, the fulfilment of their 

 destiny in that respect by Lidrogale and the macidicollis-gvow^ 

 may, I think, be confidently predicted. 



I see no reason, therefore, for making any change in the text 

 of this communication. 



* I'olile missed Paraonyx altbougli he had tlie descnptiou of congica before him 

 and apparently plontv of material of the genus in the skins and skulls of the species 

 he described as Aonyx microdon. This remark, however, is not intended as any 

 disparagement of Pohle's work, which appears to me to be exceptionally good. In 

 addition to the genera and species, it deals with geographical distribution, cranial 

 changes with growth, milk-dentition, and so forth. 



t Similarly, Pohle established " Die Snmatrana-Giu]^]K " \_=Barangia Gray] and 

 "Die jj?rt<e»s)s-Grnppe" for the American Otters canadensis, annecttns, enudris, 

 jdatensis, provocax and feJina—'A group ior which the name Lonira Gray appears 

 to be the oldest, with Lata.vina and Nutria as synonyms. 



