5 I 8 MANUAL OF ZOOLOGY. 



great extent arboreal in their habits, and in accordance with 

 this the feet are slender, and are well adapted for perching. 

 There are four toes, three in front and one behind, and the 

 former are never united towards their bases by a membrane, 

 though the base of the outer toe is sometimes united to that of 

 the middle toe. The hallux is articulated on the same plane 

 as the other toes, and touches the ground in walking. Lastly, 

 they are all monogamous, and pair for life ; in consequence of 

 which fact, and of their being readily susceptible of domesti- 

 cation, they present an enormous number of varieties, often so 

 different from one another that they would certainly be de- 

 scribed as distinct species if found in a wild state. It seems 

 certain, however, that all the common domestic breeds of 

 Pigeons, however unlike one another, are really descended 

 from the Rock-pigeon (Columba livia\ which occurs wild in 

 many parts of Europe, and has retained its distinguishing 

 peculiarities unaltered for many centuries up to the present 

 day. Finally, the young of the Columbacei are born in a naked 

 and helpless state, whilst those of the Gallinacei are "preco- 

 cious," and can take care of themselves from the moment of 

 their liberation from the egg. 



Of the various living birds included in this section, the true 

 Pigeons (Columbidce) are too well known to require any de- 

 scription ; but the Ground-pigeons (Gourida] depart to some 

 extent from this type, being ground-loving birds, more closely 

 allied to the ordinary Gallinacei. The only other member of 

 the sub-order which requires special notice, is the remarkable 

 extinct bird, the Dodo (Didus ineptus), which seems certainly 

 to belong here, though its size was gigantic, and some of its 

 characters very anomalous. The Dodo may, properly speak- 

 ing, be said to be extinct, since it no longer occurs in a living 

 state ; but it is not extinct in the sense that geologists speak of 

 " fossils " as extinct ; since it has been extirpated by man him- 

 self within quite a recent period in fact, not more than three 

 centuries ago. The Dodo was an inhabitant of the Island of 

 the Mauritius up to the commencement of the seventeenth cen- 

 tury, and was a large bird, considerably over the size of a swan. 

 All that remain nowadays to prove the existence of the Dodo 

 are two or three old, but apparently faithful, oil-paintings, two 

 heads, a foot, and some feathers, to which a few bones have 

 recently been added. The Dodo owed its extermination to 

 the fact that it was unable to fly. The body must have been 

 extremely weighty, and the wings were rudimentary and com- 

 pletely useless as organs of flight. The legs, were short and 

 stout, the feet had four toes each, and the tail was extremely 



