There are two locations for these. LOC -3199, -5386, -432 has 5. and -2355, -4733, -435 has 4. There are also egg sacks that when killed may spawn hatchlings that count towards achievement. Respawn is approx 15 minutes.
Achievement: Witch Mount? The achievement is 'optional' as it does not directly contribute to the "Progressive", "Highly Decorated", "A Force of Nature", or "Megadeath" achievements. It is nested under "Spin Me Right Round" achievement in the Progressive achievement.
There's an achievement, that does not have a link to (on the EQ Zam site), called Spider Bear. You have to kill 50 Ursarachinids. It's an optional achievement. Any way we can add this to the Zam site?