Ancient Egyptian Dances by Irena Lexova
Because Amazon and other vendors list the publication date of the English translation (1999), many people don't realize this book was actually published in 1935. It is a true academic treatise on Ancient Egyptian Dance.
The book started out really dry but if you can get past the academic writing style there are some very interesting descriptions of how and why dancing was done. I particularly liked the explanation of how movement was performed. One of the first descriptions of leg movement describes the Saidii style of kicking up one leg into a 90 degree angle as the weight bearing foot bounces off the heel.
The illustrations are reproductions of actual ancient art. The most difficult thing about reading this book is that the illustrations are all appended at the end of the book and you spend a lot of time flipping back and forth.
This book, even though thin, is by no means a light read. I had to sit down with great intent to make it all the way through. I think any dancer interested in the ancient history of the dance should add this book to his/her bookshelf.