Joe Weatherly stresses from the beginning that knowing your subject, knowing the anatomy is the only way to accurately draw. If you know the animal, you can draw him from any angle or position with or without a live example. This is true even in quick gestures. As a result he offers no shortcuts and no formulae, just a sound, understandable method by which you can construct anything.
Weatherly backs up what he says with hundreds of beautiful, lively examples using many different mediums and in many different styles. The idea is not to copy his drawings, but to see the possibilities.
I also enjoyed Jack Hamm's book, but I will say that this one wins easily. Hamm's is more of a formulae book, showing you exactly how to draw this or that animal in a particular pose. This may be comforting for early beginners, but it won't lead you close to true mastery. Also, the difference in method between Hamm and Weatherly clearly produces different finished products. Weatherly's animals are enfused with life and action, while Hamm's seem more static in comparision. This is the result of Weatherly's laying down action lines before constructing the figure.
A definite must for drawing animals or any form of life