Arnold week continues on prime-time TV. Last night it was Roseanne on ABC's "Roseanne." Tonight it's Tom on CBS' "Tom." The first-name titles are similar; the quality of the two sitcoms is not.
* "Nova: 'In Search of Human Origins' " (8-9 p.m., WMPT, channels 22 and 67) -- One interesting thing about this concluding episode is that the theories being discussed -- especially about the migrations of prehistoric man -- may have been affected, and even negated, by scientific findings released only last week, dating remains of human origins much earlier than originally suggested. PBS.
* "Beverly Hills, 90210" (8-9 p.m., WBFF, Channel 45) -- Shannen Doherty goes to jail this week -- which probably wouldn't surprise anybody, except that this time it's in character. It's Brenda who does not pass go or collect $200. Elsewhere on the show, one of the guest stars is Teri Austin, who heated up "Civil Wars" so effectively last season. Fox.
* "The Critic." (8:30-9 p.m., WJZ, Channel 13) -- This is the penultimate episode of "The Critic," with a guest-voice roster that includes Jimmy Breslin, Phil Hartman and Adam West. ABC.
* "Tom" (8:30-9 p.m., WBAL, Channel 11) -- "Better close the windows," Tom tells one of his five kids. "It's tire-burning day." Tom Graham (Arnold) and his wife, Dorothy (Alison LaPlaca), live, with their five kids, in a trailer on a construction site, where Tom is slowly and not very surely building their dream house. The five kids have individual identities, which is rare for this populated a sitcom, and the pilot contains a funny line or two -- but unlike "Roseanne," where everything has the ring of truth, "Tom" has the ring of make-believe. People exchange punch lines rather than talk, and there isn't a single unpredictable curve from start to finish. "Tom" isn't awful, but the pilot is surprisingly, almost relentlessly, average. CBS.
* "John Jakes' 'Heaven and Hell' " (9-11 p.m., WJZ, Channel 13) -- Last of three parts. If you watched the first two "North & South" miniseries, and plan to watch tonight's concluding episode to complete your viewing of the trilogy, you will by then have clocked 30 hours with this particular Civil War story. Best actors tonight: Steve Harris as Magic Magee and Lesley-Anne Down as Madeline. ABC.
* "New York Stories" (9 p.m.-midnight, USA) -- Martin Scorsese's "Life Lessons," in which Nick Nolte plays a painter unhealthily obsessed with a model (Rosanna Arquette), is the best of the short "Stories" presented in this fine 1989 comic compendium.