The Fox Children’s Network, which last year built a commanding ratings lead over its syndicated and network competitors with such top-ranked shows as “The Mighty Morphin Power Rangers” and “X-Men,” has translated that lead into sizable upfront advertising numbers this year.

According to the weblet’s sales department, Fox has grabbed $ 160 million in upfront advertising for its new fall lineup — roughly a third of the total upfront market and more than Fox took home a year ago.

Even more significant is that FCN produced these numbers before it could offer buyers a firm schedule, as Fox sold time based on show concepts alone.

As late as Monday night, FCN prexy Margaret Loesch was finalizing deals with production companies for the weblet’s five new kids series.

The most ambitious of the five are “Jim Henson’s Nature Series,””Rimba’s Island” and “Johnson and Friends,” three new preschool strips that will be launched under the banner “Fox’s Cubhouse” airing on a rotating basis at 8 a.m. Fox has placed orders for 26 episodes each, bringing the total order to 78 for the “Cubhouse” strip.

The shows, aimed at the 2- to 5-year-old audience, will challenge PBS’ virtual lock on the preschool market and compete directly with Nickelodeon’s newly announced toddler fare.

As expected (DailyVariety, April 4), FCN will also add “Spider-Man” and “The Tick” at 9 and 10:30 a.m., respectively, Saturday mornings, rounding out a two-hour action block

Saturday’s “Bobby’s World” will become a Monday-through-Friday strip in the 7 :30 a.m. slot. Also making the jump to a daily slot is “Taz-mania.”

FCN’s weekly schedule, too, has been revamped, with “Batman” moved to Saturdays and “Merrie Melodies” and “Tom & Jerry Kids” gone. “Steven Spielberg Presents Animaniacs” will do double duty Saturdays and as an afternoon strip.

Fox also confirmed plans for a six-part animated miniseries in December, based on the standup routines of comedian Louie Anderson, titled, “Life With Louie.” If the shows fare well, Fox may roll out an Anderson series in fall 1995 . An animated miniseries based on sci-fi writer Robert A. Heinlein’s “Red Planet” will air in May.

The web is also mining its 20th Century Fox film library, planning an animated miniseries based on “Planet of the Apes.”