that connect the Orders and Families of Birds. 497 



before us directs us at once to the typical families of the present 

 order. The groups that are most truly oceanic will be those which 

 exhibit the greatest deficiency in their powers of flight and of 

 motion on land. Thus in the typical I^atatores, the backward 

 position of the legs, which are thrown entirely behind the equili- 

 brium of their body, almost totally deprives them of the faculty of 

 walking ; while their wings, considerably shorter, and less covered 

 with feathers than those of any other birds whatever, bespeak 

 their incapacity of maintaining a constant or sustained flight. On 

 the other hand, these birds exhibit a superiority in the powers 

 which contribute to their support in their own peculiar element. 

 The feet, which by their position and structure are not calculated 

 for the usual offices which these members perform on land, are 

 admirably adapted to the purposes, more appropriate to the 

 Natatores, of swimming and diving. In the same way the wings, 

 which serve as feeble supporters in their progress through the air, 

 answer admirably as fins to facilitate their movements in the 

 water. Those birds then will form the typical groups of the pre- 

 sent order, which, like the Colymbus and Alca of Linnaeus^ have 

 short and slightly-feathered wings, and whose legs are so far 

 thrown backward as to give them an almost erect appearance 

 when on the ground. They will be found to be constant inhabi- 

 tants of the ocean ; and although in some instances, as the Apte- 

 nodytes of Linnaeus, they are deprived of the powers of locomotion 

 common to other birds, by the deficiency of their wings, they may 

 yet pursue their prey at considerable distances from land. To 

 such situations they must of course be conveyed by their superior 

 powers in swimming. The aberrant groups, on the other hand, 

 will be those where the powers of the wings are more considerably 

 developed, and where the legs, thrown more forward, enable them 

 to walk with comparative ease. They thus appear in general to 

 come more near the land-birds than the typical families of the 



order. 



