viii OSTEOLOGIA AVIUM. 



If divisions of birds are made strictly according to the above qualities, we shall find 

 many that do not come up to the greatest perfection of development of each particular 

 power, but are endowed with a modification of it, or with an admixture of two or 

 more of them, and some cases in which the divisions above mentioned are scarcely 

 recognizable in consequence of this admixture. It is in these cases that anatomy comes 

 to our assistance, and helps us to group and point out the orders and families that are 

 allied. 



The first three orders belong eminently to the first group, or those which are endowed 

 with great power of flight, with a modification among the Owls and Goat-suckers, the 

 softness of the feathers enabling them to approach their prey unawares. The Owls also 

 and the whole of Omnivores have the sense of hearing highly developed in addition, as 

 it is the habit of many of them to sit perched upon some tree or stone until prey 

 approaches, when they give chase ; their acute sense of hearing, therefore, assists them 

 materially in detecting its approach. 



The second order, Volitores, has quickness of flight in the greatest degree of deve- 

 lopment known among birds, and consequently has a corresponding arrangement of 

 wing differing from other birds. The food of the Humming-bird is insects, obtained 

 in two ways — by the insertion of the tongue into flowers, and also by direct chase. 



The orders Prehensores, Scansores, and Erucivores have their feet adapted chiefly for 

 climbing. The first, or Parrots, are an exceedingly curious group, and use the bill for 

 climbing equally with the feet ; the latter are also used for the purpose of holding their 

 food while in the act of devouring it. 



The highest powers of true climbing, where the feet only are used, we find among 

 the Scansores or Woodpeckers, which are able to run along the perpendicular and 

 horizontal boughs of trees with the greatest facility. 



Many of the Erucivores have the toes placed in pairs, two before and two behind ; 

 but, except in this structure, they do not agree in any particular with the other climbers. 

 One group among them, the Turacoes, are without this structure. Many of them feed 

 much on the ground, and have an elongated hind toe. The power of climbing is 

 doubtless useful to them in searching for their food, which consists principally of 

 caterpillars and insects. 



The Insessores or Perchers appear to have been hitherto a sort of refuge for the 

 destitute, as almost all birds were placed in it for which no convenient place could be 

 found ; as constituted, however, in the present arrangement, the only deviation that I 

 am aware of from the general type of skeleton is in one family, the Menuridse, in 

 which case I have followed the example of my predecessors and placed it in Insessores, 

 because I do not know where else to put it. The next three families, Certhiadae, 

 MelliphagidEe, and Paridse, have a decided scansorial tendency, but very much modified, 

 the toes being placed three in front and one behind; but although their powers in this 

 particular are quite equal to that of the Woodpeckers, there is nothing in the skeleton 

 which differs from the Insessorial type. 



