will be able approximately to appreciate the feelings with which 

 the naturalist travels from place to place ; wherever he may be he 

 finds friendly forms. For years he has silently watched the 

 interior economy and household arrangements of animated nature, 

 and get he has not seen all ; and on this account, he is never in 

 want of employment. Every bird is a personal friend, the old ones 

 he knows almost as well as he knows himself, and the new ones 

 must be studied. How much more is there yet to observe ! Rich 

 as he may be in experiences, every fresh ramble brings him fresh 

 mental treasure. The relations existing between him and the 

 bird become each day more and more intimate ; he knows the lives 

 and habits of each ; when each arrives or takes its departure ; 

 where is its abode ; how it is made ; when it is occupied by a 

 happy troop of nestlings ; when deserted. The naturalist knows 

 his friends by their notes, flight and bearing. Every new bird 

 raises his spirits a step higher ; every fresh discovery is a step 

 onward in the knowledge of the ways and means of all things. He 

 is indebted to his friends for many a happy hour ; their lives are a 

 pattern worthy of imitation." 



Here then we may ask — What is a bird? How can a bird be known 

 from all other vertebrate animals ? The chief character which distin- 

 guishes the class of birds is undoubtedly i/te clothing of the body with 

 feathers. Other characters they also possess but not exclusively. 

 For instance they have the power of flight developed in the highest 

 degree ; but there are some birds, such as the Apteryx, the Ostrich 

 and the Cassowary which cannot fly at all ; while on the other hand, 

 there are flying mammals, such as Bats, and in a less degree Flying 

 Squirrels, and there are reptiles, which can progress through the air 

 by means of flight. Again, birds lay eggs from which they produce their 

 young, hnt so do many reptiles and fish, so that this cannot be considered 

 a prerogative of the class of birds. Their bill is hard and sheathed 

 in horn, but so is that of the Duck-billed Platypus a mammal, and 

 Turtles also have beaks. Most but not all birds build nests, and in 

 this they stand almost alone among the higher animals, but still 

 nest-building propensities are developed in many of the Mam- 

 malia, in the Lemurs and Mice, for instance — while some fish also 

 build wonderful nests. But all birds, whether they fly or not, are 

 clothed with feathers, and this distinguishes the class Aves in the 

 existing state of nature. The majority are specially adapted for 

 flight, and as this is undoubtedly the most vigorous form of loco- 

 motion, the greatest muscular efforts being required to raise and 

 sustain a body above the ground and to propel it rapidly through 

 the air, a large development of muscular energy is necessary. The 

 great strain on the circulation of the blood is met by a heart, not 

 only as complete as in the Mammals, but with stronger mechanism 



