I have been scouring my 1e rulebooks to find any reference at all to the ability for characters to correctly identify monsters. I had thought that Rangers had that ability but I was wrong. I could not find any reference to that ability under Rangers (or Druids) in the 1e PHB. How is monster identification handled in 1e?
Monster identification isn't an available ability
AD&D follows the “challenge the players, not the characters” ethos of D&D that has mostly be removed in later editions. To identify a monster, the players have to make active efforts to learn the skill of monster identification, and apply it to the evidence their characters encounter.
Part of the reason for this is the basic conceit that any given AD&D 1e DM's world is potentially different — AD&D's DMG contains the explicit encouragement to vary monsters to prevent “but the book says”-itis in players.
Ways to identify monsters:
- Encounter one before and learn what it does.
- Talk to locals who have information on local monsters.
- Research monsters, via consulting with sages, searching libraries, and other in-character information sources.
- Recruit local hirelings specifically for their familiarity with local monsters.
But the primary source is really the first one. As a player, learn from experience.
AD&D just isn't a game where PC skills and abilities are primary. For anything that a player can already do to play the game “better”, the PCs don't generally have rules to do it for the players.
You may have been thinking of the Ranger's "Identification of tracks" ability introduced in the Unearthed Arcana (pg 21-22). Although it doesn't explicitly say that the Ranger can identify creatures, it does allow the ranger to identify the tracks of increasingly obscure creatures with higher levels, e.g. very rare woodland creatures at level 6 and "all sorts of creatures (woodland and otherwise) within a 100-mile radius". I suspect that many players and DMs would be at a loss to explain how this works without assuming that an implicit knowledge of at least general descriptions of many, many types of creatures must come with this ability: "Aha! Korred tracks!" "What's a Korred?" "No clue, I just get a 'Korred' feeling from them." Was this intended to apply only to previously encountered creatures? This seems unlikely, since the 10th level variation applies explicitly to "all creatures ever encountered" and the other leveled-ability descriptions do not include that phrasing.