A planet of the vast, slug-like Lactrans, who keep the Enterprise landing party in a zoo in The Eye of the Beholder.
Lactra VII is the homeworld of the Lactrans, a species of huge, slug-like telepaths with intelligence far beyond human understanding. In The Eye of the Beholder, the Enterprise follows a lost scientific team to the planet and finds their ship, the Ariel, abandoned.
Kirk, Spock and McCoy are captured and placed in a zoo enclosure, along with survivors of the Ariel's crew. A young Lactran beams up to the Enterprise and its parents learn that the visitors are intelligent, and they release the captives.