From the Introduction:
The revised Volume 1 has been updated with the new features from Volumes 2 & 3 – full color illustrations, detailed theme information, suggested knowledge tables and counter sheets. These features are now standard for the entire series. Each critter has a table to aid GMs in determining what characters know about it on a successful Knowledge check. In addition, counters (front and back) for all critters in the book have been included after the statistics pages.