22 A BOOK OF WHALES 



of the digits to which they belong ; they are situated 

 some way in front of this point, and the limb is 

 continued beyond them as a cartilaginous rod, not 

 divided up into separate phalanges. It seems, there- 

 fore, that this cartilaginous continuation, superadded 

 to the bony phalanges which lie on the proximal 

 side of it, can have nothing to do with the hyper- 

 phalangy of the whales. But the explanation, or 

 attempted explanation, of hyperphalangy is a matter 

 which will be treated of presently. As to the 

 Manatee, nails are present or absent, evidently there- 

 fore on the wane, as might be expected in marine, 

 or at least aquatic, animals, which have been longer 

 denizens of rivers and the sea than have the Sea- 

 lions ; longer in all probability, that is to say, since 

 their adaptation to the aquatic life is more complete. 

 Manatus inunguis is so named on account of the total 

 absence of nails upon the hands ; this has been 

 noted by several writers, and there can be no doubt 

 about the matter. Now it is precisely in the group 

 of the Sirenia that hyperphalangy is also met with, 

 but to a very small extent nothing like what we 

 find among the whales. Finally, among the Amphibia 

 the same phenomenon is met with, so that the 

 occurrence of hyperphalangy may, as it seems, be 

 fairly set down to the need for an increased surface 

 of hand to form a competent paddle. A very 

 singular fact about this hyperphalangy in the whales 

 is the existence of more numerous phalanges in the 

 young than in the adult. Thus in Phoc&na communis 

 the phalangeal formula of an embryo seven cm. long 



