Several years ago I was much struck by a remark to the above effect made by Mr. Waterhouse.

Professor Owen, also, seems to have come to a nearly similar conclusion.

It is hopeless to attempt to convince any one of the truth of the above proposition without giving the long array of facts which I have collected, and which cannot possibly be here introduced.

I can only state my conviction that it is a rule of high generality.

I am aware of several causes of error, but I hope that I have made due allowances for them.