352 Canadian Record of Science 



sing. But it is doubtful whether there is anything that 

 can exactly fill the place of the beaver in the natural 

 and national life of Canada, if it should vanish from the 

 scene. 



The flattened scaly tail is not the external feature 

 which renders the beaver unique. Alone amongst mam- 

 mals the beaver has an arrangement on the second toe of 

 each hind-foot for cleaning the fur. At first sight it 

 looks like a double claw and was so described by Cuvier 

 and many later writers, including Audubon and Bach- 

 man, Lewis Morgan, E. T. Seton, and others. So far as- 

 I have been able to ascertain, the suggestion that it 

 serves as a cleaning claw first emanated from D. Girtan- 

 ner (op. cit. 1885). He noticed that alongside and below 

 the normal claw of the second hind-toe there is an acces- 

 sory "nail-plate," which can only serve to comb the 

 flanks of the animal, the heavy paunch deriving advan- 

 tage from such a special provision to facilitate cleaning. 

 E. T. Seton (op. cit. 1909, Vol. I. p. 469), figures what 

 he calls "the split nail of the second toe on hind-foot, ' r 

 which he thinks may be "possibly for use as a comb and 

 louse-trap." 



What seems to be an accessory claw on the second 

 hind-toe of the beaver is in reality a crest-like ridge 

 developed from the nail-bed in front of and below the 

 regular claw. The upper free rim of this crest is corni- 

 fied and presents a sharp edge to the true claw, leaving 

 a narrow chink through which the fur can be combed. The 

 crest- is a specialization of the lip of the claw-bed; this is 

 continued round the outer side of the base of the claw 

 and produced forwards as a vertical crest. Only the 

 edge of the crest is hard ; the sides are soft and filled 

 with dense white fibrous tissue like the substance of the 

 toe-ball. The claw is not separately movable upon the 

 ridge ; they move together as one piece with the terminal 

 phalanx with which they are connected. 



If we seek for analogies for the cleaning claw of the 

 beaver, we should find nothing like the mechanism just 



