From the back cover:
Are you ready to face the horror of the Hivebrood, the gruesome Geonid or the dread Dusanu? These and many other baleful beasts lurk within the pages of this manual, waiting to challenge even the mightiest adventurers!
The Creature Catalogue is the first major expansion to the range of D&D® game monsters. Within its covers have been collected all the curious creatures first presented in the official D&D® adventure modules, plus many more new nasties, designed to challenge and perplex the heartiest heroes. Also included is a comprehensive index of all D&D® monsters found in the Basic, Expert, Companion and Master rulesets.
Whether your players' characters are 1st, 21st, or 31st level, this tome contains many fantastic creatures with which to test their mettle. Armed with the Creature Catalogue, you will be able to find the right fearsome foe to confront even the most foolhardy fellow.