OSTEOLOaiA AVIUM. 



IX 



All the other families of Insessores are more or less perching birds, which may be 

 defined as a power of climbing very slightly developed. Two groups, the Motacillidae 

 and Anthidae, have the lengthened hind claw common in many groups of ground-feeding 

 birds ; we find in them, therefore, a power of scratching and running joined to that of 

 climbing; and amongst the Hirundinidae or Swallows, a considerable power of flight 

 joined to that of perching. 



The eighth order, Bipositores, are a group well defined, having a large crop, of which 

 all the families previously mentioned are destitute. In them we find a great power of 

 wing, a certain degree of migratory habit, and feet in general much better adapted for 

 perching than for scratching ; thus the farmer often says that he does not mind the 

 Pigeons on his new-sown wheat, as they do not scratch, merely taking that which is on 

 the surface. There are, however, a few exceptions, as the Crowned Pigeons, which have 

 feet fitted for running and perching, the metatarsi being much lengthened. Dr. Melville 

 has discovered a peculiar structure in this part, which distinguishes the Pigeons from 

 other orders, and unites the extinct family of Dodos with them. Generally the Pigeons 

 only lay two eggs, whence the name I have given to them. 



The Easores I have divided into two groups, the Tetraonidae and Phasianidae, although 

 there is no very distinct line of demarcation between them. The typical species present 

 a very great difference in external form, even if it is merely in the development of the 

 tail— for instance, between the Partridge and Peacock. Both are gifted with great 

 running and scratching powers, but without any great powers of flight ; consequently 

 none of them, that I am aware of, are migratory. The typical species of the former 

 roost on the ground, seldom perching in trees, while the latter almost invariably do so. 

 They both have a moderate-sized crop; but it is not nearly so highly developed as 

 among the Pigeons. 



The Cursores are adapted solely for terrestrial life, and have no power of flight ; con- 

 sequently we find the greatest development in that of running, the rudimentary wings 

 being employed as a sort of oars to assist in their progression ; they may be considered 

 as the types of running structure among birds. 



The eleventh order, Littores, have great power of running, but not nearly so much 

 as in Cursores, which might be expected when the power of flight is largely developed 

 also ; for, throughout the animal kingdom, one power is never found largely developed 

 except at the expense of another. Their legs also are fitted for wading in shallow 

 water, the tibiae not being feathered down to the metatarsus. 



The twelfth order, Grallatores or Waders, have a very great length of leg, the tibiae 

 much denuded, and a formation of the joint between the tibia and metatarsus so 

 contrived that they can stand for hours together without muscular action (Ardeidae) ; 

 and in the following family (Eallidae) we find the fitness for wading diminished, and a 

 development of a power of swimming. 



The powers of the next order are at once well defined by the name Natatores, or 

 swimming birds ; and the whole of the members of it have either webbed or lobated 



e 



