As with many publishers it can be difficult to date an Altemus book. If you keep in mind several points, it can be made a bit easier.
1. Altemus published books for reading (non-Bibles from 1889-1933)
2. Henry Altemus incorporated in 1900. Thus books which have Henry Altemus Company on the title page were printed after 1899. (1900 or later)
3. Henry Altemus Company frequently left the earliest publishing date on the title page. Thus a 1904 title page with Peter Rabbit appears on all of the later reprints.
4. Henry Altemus did virtually all reprints. Those Alice in Wonderland, Kipling, Doyle, Dickens etc. are all one of a myriad of reprints.
5. All Altemus books came with jackets or in boxes. (except for a few paper backs)
6. The earliest Peter Rabbit has half vellum and an oval with a picture on the front cover. All others are later reprints.
7. Altemus jackets were uncoated brown until 1915. After that they were white coated.
8. The Alice in Wonderland books most often seen are later reprints. Look at the title page to see if it says Henry Altemus Company or not (post 1900 if it does).

Email me and I will be happy to tell you about the book you have or are considering bidding on.  Also I can give you an estimate of the Altemus book's value. My website at henryaltemus.com . Look up your book in the index for specific information.
Cary