THE CLASSIFICATION OF BIRDS. 255 
The principal schemes for the classification of Birds which 
have appeared since Cuvier’s are those which have been pro- 
pounded by Lilljeborg*, Huxley *, Sundevall *, Garrod‘, Sclater ’, 
Newton °, Reichenow’, Stejneger *, Fiirbringer °, Seebohm "°, 
Gadow **, and Sharpe’. 
Mr. Henry Seebohm deserves exceptional credit for having 
given us a classification founded on absolute diagnostic 
characters, by which, for the first time perhaps, the definite 
characteristics of the leading groups of Birds have been 
clearly summarized. On this account we gladly avail our- 
selves largely of his labours, and follow his grouping to a 
very great extent. 
We will shortly proceed to enumerate the principal groups 
into which we think the Class of Birds is thus divisible, and to 
give the characters of such leading groups. The classification 
here offered is, however, put forward only in a tentative manner 
and with much diffidence, as one which we think may be found 
practically useful. But, before we proceed to the enumeration 
of the groups, we would endeavour to stimulate and arouse the 
interest of the Student by pointing out some striking examples 
of errors into which we should fall, if we rested content with 
merely superficial characters, such as we have mainly referred to 
in our introductory chapter. 
Birds may be shortly defined as feathered animals, since no 
other animals possess such structures. They are, however, 
Vertebrate animals with warm blood and anterior lmbs 
peculiarly modified. The skull always articulates with the 
vertebral column by a single occipital condyle’, and the lower 
' Proe. Zool. Soe. 1866. Seis VAS Sh shoe 
* *Methodi Naturalis Avium Disponendarum Tentamen,’ Stockholin, 
1872. 
+ P. Z. S. 1878 and 1874. > This, 1880. 
® Ency. Brit., Art. “ Ornithology ” (wherein a full and admirable account 
of the history of the science and of the works of its promoters is to be found). 
7 Die Vogel d. Zoolog. Garten, 1882. 
5 Standard Nat. Hist., Aves, 1885. 
° Morphologie u. System. der Vogel, 1888. 
10 “Classification of Birds,’ R. H. Porter, 1890. 
Pp. Z. 8. 1889, and Bronn’s Thierreich, Aves, 1890. Also a paper read 
before the Zoological Society while these pages were being revised for press 
—March, 1892. 
* ©A Review of recent attempts to classify Birds,’ 1891. 
‘8 By which character Birds differ from man and beasts, where there are 
two occipital condyles. 
