Page:Transactions of the Linnean Society of London, Volume 12.djvu/603

Rh occupation the bird is often engaged for a considerable length of time), its weight is thrown backward, and thus the supply of two toes behind is rendered extremely necessary for its support.

What makes me think the wise Author of Nature had this end principally in view is, that the Nuthatch, from the want of this conformation, is, when breaking nuts, under the necessity of sitting with its head downwards. It may be alleged that its flexible tail compels it to this position; but, as I have before observed, it runs up trees with equal or greater facility than the Woodpecker, notwithstanding that disadvantage.

It would be a curious circumstance, and a conclusive argument in my favour, should it ever be ascertained that the three-toed Woodpecker {Picus tridactylus ), which has only one toe behind, bores trees in the attitude assumed by the Nuthatch when breaking nuts. I have now brought this letter, which I fear has tired your patience, to a conclusion; but as it is upon a subject hitherto not sufficiently examined into, you may possibly think it worthy of being communicated to our scientific brethren.

XXXII. An