41 



of vertebrates. In fact, there is not as much difference between the extremes 

 of living birds as there is between representatives of a large order of reptiles 

 or tishos. Nevertheless, there is adaptation among the birds for almost as 

 many functions and habits as in any other class. This adaptability is evident 

 in the degrees of power of flight, the use of tiie feet, the food and mode of ob- 

 taining it, and the condition of the newly hatched young. 



VAIUATION IN FLIGHT. 



While the osseous framework of the fore limbs of all living birds is almost 

 always essentially the same, so far at least as the numl)er and relative propor- 

 tions of the bones are concerned, the variation in their covering is great. The 

 extremes are manifest in the wings of the swallows on one hand and in those of 

 the ratite or ostrich kind and the penguin family on the other. In the ratite 

 birds the bones are reduced to a minimum of size and, in a family (the 

 Moas or Dinornithids) extinct within the life-period of mankind, were entirely 

 atrophied. 



Although in the ratite birds alar reduction is carried to the greatest 

 extent, in various other birds the wings were more or less reduced or de- 

 functionalized. Among such were relations of the Pigeons — the Dodo and 

 Solitaire of theMascarene Islands; a gigantic Rail, the ^^Geanf" {Aphanapteryx 

 boechli), also of the Mascarone fauna (Mauritius); the great Auk {Plautus 

 impomis); and the largo Alaskan Cormorant (^Phnlacrocorar pempicUlatus): 

 the inability to fly was partially at least the cause of the extinction of all. 



Among birds still living may be mentioned the steamer or logger-headed 

 Duck of Patagonia [Tachyeres cinereus), and the Owl-parrot {Stringops 

 Imhroptihis) of New Zealand, whose power of flight, in the adults at least, is 

 reduced almost or quite to nullity. Other still living flightless birds of New 

 Zealand are Rails, related to the extinct "Geant" of Mauritius, known 

 as Woodhens and about as large as an ordinary domestic hen. Some smaller 

 flightless Kails of various Polynesian islands have become exterminated within 

 recent times. 



Even more remarkable than them are the Penguins of the Southern seas, 

 in which the fore-limbs have the function and even the appearance of fins 

 rather than of wings. 



It is especially noteworthy that these brevipinnate or short-winged birds 

 are related to various types that have wings fully developed for flight, and 

 this remark holds good even for the Ostriches, for they are now generally 

 admitted to be most nearly related to the Tinamous of South America which 

 are capable of flight to the same extent as the Quails and Partridges, of which 

 they are the analogues, and which they resemble so much superficially, 

 although very difl'erent anatomically. The obvious inference then is that, so 



