The animated series is on a bit of a roll, with another good episode following The Slaver Weapon, though this time offset by the usual silly antics of Kirk beaming down recklessly into danger to precipitate the drama. The Lactran aliens are eerily enigmatic, in that they never make a sound during the episode, nor do we hear their telepathic communications - so we only have the visuals and the descriptions of Spock's attempts to communicate with them to go on. This lends them a truly other-worldly quality that is often missing from alien species in Star Trek.

I also learnt to some frustration that there is also an episode of Star Trek: The Next Generation titled Eye of the Beholder, which made it somewhat tricky to restrict my searches to information related to the animated episode. (And furthermore, there is also an episode of Degrassi: The Next Generation titled Eye of the Beholder!)

Transcript

1
Captain's log, Stardate 5501.2. Search party for science team missing on Lactra VII.
McCoy: My shoes are full of sand.
Spock: Doctor, your lack of scientific interest is amazing.
McCoy: I don't like sand. It's coarse and rough and irritating and it gets everywhere. Like you, Spock.
2
{They are captured by giant slug-like aliens with proboscis tentacles}
Kirk: Odd terrains, animals recycled from other episodes...
McCoy: And these creatures putting us in a force field cage.
Kirk: We're in a zoo!
3
{inside the cage}
Markel: I'm Commander Markel, good to see you.
Kirk: As officer in command, you neglected your duty by beaming into danger yourself!
Markel: Riiight...
4
Spock: These telepathic aliens are far in advance of us. We are but animals to them.
McCoy: I've seen the way we treat aliens we don't understand. We're boned.
5
Scotty: I befriended this baby alien you accidentally beamed up.
Spock: We have been trying to communicate, fruitlessly. How did you do it?
Scotty: Well-
6
Kirk: Never mind explaining that! We're all friends now! Let's go!
McCoy: Yippee!!