REVIEW OF BIEDS. 437 



classification held forth. As the wings must be considered to he of the highest 

 importance to a bird, being among those parts that indeed make him a bird, it 

 is natural that a system in which the structure of the wings has been consid- 

 ered should be preferable to any other where the wings have been neglected, or 

 tliis subject but slightly touched upon, without any minute examination of their 

 Btructure. The above-mentioned author has, in his " Svenska Foglarna," ob- 

 served the muscular structure of their feet as important in classification, fifter 

 having previously, for the first time, called attention to the same at the meeting 

 of naturalists in Stockholm, in 1851. 



Tlie new genera and species that have been added since Latham's " Index 

 Oraithologicus" was edited had increased to such a number, and their literature 

 had become so scattered, that such a work as G. R. Gray's systematic " List of 

 the Genera of Birds," although only a list of names without characters, was 

 very necessary to science, and the obtaining of the same, also highly beneficial. 

 The right of priority has generally been observed in this work. The same au- 

 thor has, in his " Genera of Birds," given descriptions of the orders, families, 

 and genera, and even figures of the same. A single species of some genera is 

 represented by a colored figure ; and of others only certain parts, such as the 

 head or the foot of some typical species, have been figured. This work is cer- 

 tainly of great value for the study of birds ; and the very good figures often 

 give a necessary explanation to the descriptions of the genera, which at times 

 are but little distinguishable, and are not given in a diagnostic manner. 



Cabanis has, in his ornithological system, given good characters for the ar- 

 ranged groups, taken partly from J. Muller's descriptions of the inferior larynx, 

 partly from the nature of the horny covering on the tarsi, first studied by 

 Keyersling and Blasius, and partly from the number of quills and tail-feathers. 

 It is principally the order Passeres to which this author has devoted bis atten- 

 tion, and which consequently has obtained an improved classification. It has 

 l>een divided into two groups, (Oscines and Clamatores,) and the families have 

 been carefully limited and arranged. This work, with that of Sundevall, may 

 rightly be considered most important in the classification of birds. 



The numerous contributions to this classification that have been made by 

 Bonaparte are valuable as giving minute registers of families and species, show- 

 ing an unusual knowledge of the species, and a sharp distinction between the 

 genera, and often arranging these in a manner corresponding with the demands 

 of the natural affinity ; but they are generally only registers of names, often 

 giving the characters for the species, but very seldom for the higher groups. 



Bonaparte has published, in the " Transactions of the Linneau Society," 

 xviii, p. 258, a systematic arrangement of the class of birds, together with tlie 

 classes of the other vertebrated animals in general. The first class has been 

 divided into two sub-classes — Insessores and Grallatores. The first of these 

 corresponds fully with the one arranged by us under the same name, and the 

 latter includes both Grallai and Natatores. This classification corresponds also 

 with the one given here, in the Longipennes having their place between the 

 Steganopodes and the Pygopodes. Characters of the orders, families, and sub- 

 families are also given. 



After this brief reference to the literature, we will proceed to a synoptic 

 statement of the principles upon which the systematic arrangement here givea 

 rests. 



PRINCIPLES. 



We have prefejp"ed the progressive method, as it seems to us to be the most 

 rational, from its correspondence with the physiological and geological develop- 

 ment. We therefore commence the system with the lowest, and finish it with 

 the highest forms. 



