Gamma Hydra II was a somewhat nondescript planet, the second planet in the Gamma Hydra star system in the galaxy's Beta Quadrant, in the Gamma Hydra sector. Captain James T. Kirk, under the effects of rapid aging, made the mistake of mentioning Gamma Hydra II when he was referring to Gamma Hydra IV. (TOS episode & Star Trek 7 novelization: The Deadly Years)