ABC, CBS and the Fox Children’s Network will tout their fall Saturday-morning lineups to advertisers this week as upfront sales for that daypart kick into full swing.Fox, the established leader in Saturday morning, is expected to bring back, in sequence, such shows as “Jim Henson’s Dog City,”"Eek! and the Terrible Thunder-Lizards,”"Where on Earth Is Carmen Sandiego” and “Animaniacs” while augmenting its super-hero appeal by surrounding its top-rated series, “X-Men,” with a new version of “Batman” that also features Robin, “Spider-Man” (likely to arrive next January) and previously announced “The Tick.” Anderson series set FCN is also said to be picking up a new series, from Hyperion Prods., that will feature comic Louie Anderson, probably for midseason or a limited-series run. Fox has a decided advantage over the other webs in that it can test short orders and capitalize on cross-promotion by virtue of its unique access to both Monday-through-Friday and Saturday-morning blocks. In addition, Fox is said to be planning a morning strip aimed at preschoolers , likely to be composed of two or more distinct programs. It’s also expected that the surprise hit “Mighty Morphin Power Rangers” will air only in the Monday-through-Friday block. CBS will likely anchor the 8 and 9 a.m. hours with two Disney movie adaptations, “Disney’s Adventures of the Little Mermaid” and “Aladdin,” wrapped around another animated feature spinoff, Universal Cartoon Studios’ “Beethoven” (Daily Variety, March 17). Another new show, “Skeleton Warriors,” is based on a popular toy line, to be followed by a half-hour of “Teenage Mutant Ninja Turtles ,” new comic-book inspired series “Wildcats” from Nelvana Entertainment, and the returning “Garfield and Friends” and FCC-friendly “Beakman’s World.” Sources say ABC will lead off with the “Bugs Bunny/Tweety” hour, followed by its own previously reported movie spinoff of “Free Willy.” Other new projects are said to include “Fudge,” a live-action series from Amblin Entertainment, the clay-animated “Bump in the Night” and computer-generated “Reboot.” Returning shows are “Sonic the Hedgehog,”"Tales From the Cryptkeeper” and “Cro.” Fox has its day Fox has been dominant in the daypart, averaging a 7 rating among the key sales demographic, children age 2-11, since the official start of the season last Sept. 18. It has regularly surpassed that level during the first quarter. Over the same six-month period ABC and CBS have averaged a 4.7 and 4.6, respectively, by that standard.