The Sci Fi Channel series "Stargate SG-1" marked its 200th episode last week, but barring intervention from other parts of the TV universe, the show won't make it to 250.

The cable network has opted not to extend "SG-1" beyond the current season, the show's 10th overall and fifth on Sci Fi (the first five seasons aired on Showtime). The show's final episodes will air early next year.

Spinoff series "Stargate Atlantis," however, will return to Sci Fi for a fourth season. Some cast members from "SG-1" may continue their roles on "Atlantis."

"Having achieved so much over the course of the past 10 years, Sci Fi believes that the time is right to make this season ['SG-1's'] last on the channel," the network says in a statement. "Sci Fi is honored to have been part of the 'Stargate' legacy for five years, and we look forward to continuing to explore the 'Stargate' universe" through more episodes of "Atlantis."

Although ratings for the show this season aren't quite at the level of previous years, "Stargate SG-1" still draws a respectable 2 million viewers per week, about half of whom fall into the adults 18-49 demographic. Sci Fi says the decision not to renew was based more on a feeling that the series had run its course than on ratings.

With 10 seasons and 200-plus episodes under its belt, "Stargate SG-1" is the longest-running science-fiction series ever produced for American television. The British series "Doctor Who" ran from 1963-89 in its original incarnation; a new version of the show debuted last year and also airs on Sci Fi.