382 THE STRUCTURE AND LIFE OF BIRDS cnap. 
same as in Mr. Mivart’s Elements of Ornithology: in 
the one the owls form a separate order, in the other 
they are a sub-order of the Raptores. Botanists are in 
a very different position: the battles of their rival 
classifiers are fought over far more minute points. 
Ought a certain form of briar, willow, or rose to be 
counted as a species or a variety? The question 
whether a particular genus shall be included among the 
rushes or the lilies is one that exceeds the ordinary 
magnitude of the problems that beset the classification 
of British flowers. 
Reptiles also, from a classifier’s point of view, present 
a striking contrast to birds. They are divided into 
great and unmistakableorders. Thereare the Tortoises, 
the Lizards, the Crocodiles, the Snakes. With birds, 
though the number of species is very great, the differ- 
ences are very small; it is only by a minute study of 
many, often obscure, anatomical points that a sound 
system of classification has been arrived at. Unfor- 
tunately a system founded on such a basis, however 
true it may be, must always have this drawback—that 
an amateur must accept a great deal of it on trust. 
I shall try to make clear a few of the chief points on 
which the best and more recent systems depend. And 
these few will be selected not only for their importance 
but because they may be understood without much 
technical knowledge. If they seem insufficient, it 
must be remembered that there is a great array of 
equally telling, but less easily appreciable, facts in 
reserve. 
There are, as I have said, eleven thousand known 
birds. The first step is easy: they can be divided 
