The beast names are listed in two ways: Alphabetic and Cross Reference. You can select which you want to see from the beast introduction page, and switch between them by clicking "Alphabetic" or "Cross Ref" at the top of the list pages.
Both lists have the same functions. The yellow bands allow you to jump directly to the sections containing beasts whose name starts with the selected letter of the alphabet. Click on a beast name to see detailed information on that beast.
The Alphabetic list shows only the "standard" name for each beast, as is used on this site. The Cross Reference list shows the standard name and all known alternate names for each beast. For each alternate name, the standar name is shown in brackets, like this: Aptalon [Antelope]. Clicking on any of the alternate names for a beast will show you the detailed information for that beast.