ANIMAL LOCOMOTION: The Muybridge Works at University of Pensilvania..

Here's a nice book for those interested in animal locomotion. It's a study on Muybridge's method and result of his work with animals at the University of pensilvania. It has a deeper explanation of how animals move around with very clear diagrams.

Like these fellas here:

And the best of it... It's public domain.
Download it here as a PDF
(Right click...save link as...for downloading it)