Here are two new pictures for this series. The 1899 books of the Petit Trianon Series were half vellum with an embossed floral decoration on the left and a floral/decorative pattern on the right. It is unclear how many different right sided patterns there are but up to this time I have found 24. They can be seen at http://henryaltemus.com/series/series143.htm .

The other picture here has a vine-like pattern on the left vellum side. It is an 1899-1900 book. As with the 1899 books, the right side has various decorative/floral arrangements. Including this book I have discovered 24 different designs.