Summary of Muscular Anatomy.
Garrod̂s hope, excited by his extraordinarily interesting pioneer work, that muscular anatomy would furnish a sure clue to the classification of birds has not been fulfilled. Garrod relied chiefly on the presence or absence of certain muscles which he found to vary from group to group. Gadow, who has attempted on a complete scale to apply to the system Garrod̂s group of muscles, using the additional facts made known by Beddard and other writers, appreciated that as these muscles were a common heritage of all birds, the presence of any of them in any group of birds could not be taken as a guide to the systematic position of that group. He was disposed, however, to attach value to the loss of any of these muscles, and accordingly regarded the loss of this or that muscle as one of the characters to be employed in judging of the relationships of groups. Even this cautious use seems to me to be going too far. At present I do not know of any reason why we should suppose that a particular muscle may not have been lost independently many times; that is to say of any reason why a bird that has lost its femoro-caudal muscle should be more nearly related to another bird with a similar loss than to a bird which has retained the possession once common to all three. The loss is what I have described as a multiradial apocentricity. Possibly when we know as much of the development and morphology of the muscles used by Garrod, as Fürbringer has taught us in the case of the shoulder and wing muscles, we shall be able to make move definite use of muscular anatomy in systematic ornithology. As, however, muscular anatomy has been used freely, I may give a summary of the chief facts from which more confident anatomists would draw inferences.