of taking an Ornithological Census. 191 
requirement of British ornithology. To this opinion I cannot 
entirely consent; but I nevertheless think that if some such 
approximate estimate could be made, it would be extremely ad¬ 
vantageous not only to English ornithologists, but to those of 
foreign countries; and that, if more generally extended to other 
branches of natural history, it might furnish results of a very 
, valuable, not to say unexpected, character. 
Just at this time, when we are on the eve of taking the human 
census of the British Empire, I think, then, it is not inappro¬ 
priate to bring a somewhat similar design as regards our Fauna 
to the notice of naturalists. With this view I am about to com¬ 
municate to the Linnean Society some remarks bearing upon 
the question of a general zoological census, while I here propose 
more especially to call the attention of ornithologists to the 
particular application of Mr. Wolley's project. 
I am not so sanguine as to hope that any immediate steps 
will ensue from this paper; but if my brother-students will but 
lend the matter their consideration, perhaps, before the close of 
the existing generation, we—or, rather, our successors—may be 
in a position fairly to begin the work. Indeed, beyond stating my 
conviction that a census of our birds merely can only be taken 
by the co-operation of nearly all the ornithologists in the 
country, I am not at present prepared to offer any suggestions 
as to the method to be employed. But I wish to make a few 
observations on the subject. 
Now as to the probable utility of such a census, to which I 
imagine many will at the outset demur. It is unnecessary in 
these days, if it ever was otherwise, to show how much light has 
been thrown upon natural history by an understanding of the 
geographical distribution of species. Yet our acquaintance with 
this extensive field of research is very limited. The six great 
physical regions of the earth's surface have been defined with 
more or less accuracy, but the details are far from being filled 
in. Meritorious efforts have been made to determine the summer 
range of the Nightingale and the lines of the Crane's simultaneous 
arrival. The progressive advance of the Republican Swallow in 
North America, of the Grey Partridge in Scandinavia, and of the 
House Sparrow in Siberia has been recorded. The respective 
