3(50 



THE VOYAGE OF TT..M.S, CHALLENGER. 



why it should not be included along with A]>teno<l)/(es lonyirostris as another species of 

 one and the same genus. 



" Lastly, in their affinities the Penguins appear to be more closely allied to the 

 Palmipedes than to any other group of birds, but tho numerous important deviations 

 which they present from every one of the various groups included within that very hetero- 

 geneous assemblage appear to show that the Spheniscidse must have diverged at an 

 early period from the primitive avian stem, and the connecting links having been lost, it 

 seems at present hopeless to attempt to establish the exact affinities of the Penguins to 

 other birds. At first sight, indeed, it appears that the nearest allies of the so-called 

 wingless birds of the southern are to be found in the wingless birds of the northern 

 hemisphere, but the researches of Professor Owen 1 on the osteology of the Great Auk 

 (Aha impernus), abundantly show that the two groups have but little in common. We 

 are compelled therefore to postpone the accurate determination of the affinities of the 

 Spheniscidae till the progress of Palaeontology shall have made us acquainted with the 

 intermediate forms connecting the Spheniscidse with the primitive avian stem from 

 which both they and the other Palmipedes were originally derived." 



whilst the latter may only express the fact that under similar circumstances anil the necessity of adopting similar modes 

 of life the details of anatomical structure of two specifically distinct organisms tend also to become similar. 



" I would only farther remark that an investigation into the entire subject of the relation which the sexual organs 

 bear to the skin and tegumentary appendages on the one hand, and to the rest of the organism on the other, in different 

 forms of animal life, is one which is likely to be productive of valuable results in enabling us to determine the essential 

 morphological as distinguished from the physiological characteristics of a species." 



1 Description of the Skeleton of the Great Auk or Garfowl (Alca impennis), Trans, Zool. Soc, vol. v. p. 31V, I860. 



