6i 4 THE POPULAR SCIENCE MONTHLY. 



and peculiar of all. Strangest among them is the kiwi or apteryx of 

 New Zealand, that almost wholly wingless bird who may be seen any 

 morning at the Zoo, gravely stalking up and down, like an important 

 political prisoner, within the small inclosure to which tyrannical cir- 

 cumstances have temporarily confined him. The kiwi has feathers 

 which closely resemble hair in texture, and his wings are so very 

 rudimentary that they can only be properly observed at a post-mortem 

 examination. His bones have no air-canals, and some of his internal 

 anatomy is very abnormal. The cassowaries of the Papuan district 

 are somewhat more bird-like in type, but they also preserve many 

 antique features, especially in the relative smallness of the head and 

 brain compared with the general size of the whole body. The Aus- 

 tralian emus approach more closely to the true ostriches, and their 

 feathers are far more feathery than those of the cassowary. In both 

 these classes, however, the small and functionless wings are destitute 

 of plumes, which are only represented by a few stiff, horny shafts. 

 The true ostriches, including both the familiar African species and 

 the South American rheas, have real wings with real feathers in them, 

 though they can only use them to aid them in running, and not for 

 the purpose of flight. They are therefore the most bird-like of their 

 order, with small wings and very feathery plumes. We may fairly 

 regard all these keelless and often almost wingless birds the kiwis, 

 cassowaries, emus, and ostriches as the last survivors of a very an- 

 cient group, immediately descended from ancestors not unlike the 

 toothed hesperornis, and never forced by circumstances to develop 

 into the full avian type represented by the swallows, hawks, and 

 herons. All of them are strictly terrestrial in their habits ; none of 

 them can fly in even the slightest degree ; and the feathers of the 

 most developed among them invariably lack the tiny barbules or small 

 hooks which bind together the cross-barbs in the feathers of the flying 

 bird, so as to form a compact and resisting blade. It is this looseness 

 of the cross-barbs which gives ostrich-plumes their light and fluffy 

 appearance ; while, pushed to an extreme in the cassowary and the 

 kiwi, it makes the plumage of those ugly birds approximate in charac- 

 ter to the hair of mammals. Though from the human and decorative 

 point of view we may admire the fluffiness of ostrich-plumes, it is 

 obvious that, looked upon as a question of relative development, such 

 loose, floating barbs are far less advanced in type than the firm and 

 tightly interlocked quill-feathers of a goose or a raven, with which 

 alone sustained flight is possible. 



Except in such isolated countries where higher mammals do not, 

 or did not till lately, exist, the power of flight, once acquired, was 

 sure to be developed in a high degree. For the possession of feathers 

 gives birds an advantage in this respect which enables even the little 

 sparrows to hold their own in the midst of our crowded cities. Hence 

 all other modern birds, except these lingering, ostrich-like creatures, 



