6 PROF. W. LIXLJEBORG ON THE CLASS OF BIRDS. [Jail. 9, 



The new genera and species that had been added since Latham's 

 • Index Omithologicus ' 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 author 

 has, iu his ' Genera of Birds,' given descriptions of the orders, fami- 

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

 some genera is represented by a coloured figure ; and of others only 

 certain parts, such as the head or the foot of some typical species, 

 have been figured. This work is certainly 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 arranged groups, taken partly from J. Muller's descriptions of 

 the larynx inferior, 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 Pas- 

 seres to which this author has devoted his attention, and which con- 

 sequently has obtained an improved classification. It has been di- 

 vided 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 classi- 

 fication of birds. 



The numerous contributions to this classification that have been 

 made by Bonaparte are valuable as giving minute registers of fami- 

 lies and species, showing 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 cha- 

 racters for the species, but very seldom for the higher groups. 



Bonaparte has published, in the ' Transactions of the Linnean 

 Society,' xviii. p. 258, a systematic arrangement of the class of birds, 

 together with the classes of the other vertebrated animals in general. 

 The first class has been divided into two subclasses — Insessores and 

 Grallatores. The first of these corresponds fully with the one ar- 

 ranged by us under the same name, and the latter includes both 

 Grallae 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, fami- 

 lies, and subfamilies 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 given rests. 



Principles. — We have preferred the progressive method, as it 

 seems to us to be the most rational, from its correspondence with the 

 physiological and geological development. We therefore commence 

 the system with the lowest, and finish it with the highest forms. 



