568 REMARKS ON THE SWIMMING BIRDS. 



that occur in the British seas and fresh waters remain to be 

 described. They all agree in possessing one obvious common 

 character, that of having their digits connected by flexible 

 membranes, formed by an upper and lower layer, or indupli- 

 cation of the skin, modified so as to adapt the feet for swim- 

 ming by converting them into paddles. The instrument thus 

 formed may be more or less complete, all the digits being 

 connected in some, the anterior three only in most, and the 

 webs being extended to the full length of the^e flexible shafts, 

 or shortened by excision, as it were, of their anterior part, or 

 even partially cut into lobes ; and birds of other groups may 

 have feet partially webbed, so as to fit them in various degrees 

 for the same office ; but all of them are web-footed, and all 

 swim. They can all walk on the water — for the natation of 

 a bird that floats on the surface is but a kind of walking, 

 though the feet be immersed in the liquid. Gradation on 

 land they are also in some measure adapted for, some in a 

 very efficient manner, others very imperfectly, a few so ill 

 that they are usually described as incapable of walking. But 

 these Palmipede or Natatory Birds present no other common 

 character, excepting those which belong alike to all the 

 groups, their organization differing so as to render it impos- 

 sible to include them all in one ordinal category. And why, 

 it may reasonably be asked, should all the web-footed birds 

 form a single order, when those that are free-toed form several ? 

 If they did, it would be contrary to analogy. 



If an order be anything else than a mere arbitrarily 

 limited aggregation of specific forms, surely a bird that has a 

 broad bill covered with a thin dense skin, and furnished on 

 the inner sides of the upper mandible, and the outer sides of 

 the lower, with series of parallel plates, of a peculiar kind of 

 cutaneous tissue, arranged like the laminae of a whale's baleen, 

 presents in these very features of its organization characters 

 so different from those of all other Water Birds, as to merit for 

 them, not family, but ordinal distinction, especially as no 

 gradation is presented between them and any other groups 

 whatever, they being as perfectly isolated as the Parrots or 

 the Pigeons. 



