two, and the Planet Of the Apes show got four.
In 1977, Dell Books commissioned veteran tie-in author Richard Woodley (The Bad News Bears, Slap Shot, Con Air) to pen four paperback novelizations of the NBC Man From Atlantis telefilms: Man From Atlantis, Death Scouts, Killer Spores and Ark Of Doom (The Disappearances). The first two of these books hit the racks just around the time the weekly series premiered in Autumn, and I remember saving up my Junior High allowance of 50¢ a week to buy them when they came out. Woodley was a solid wordsmith, so they're pretty decent adaptations - and good reads, too.
Vincent DiFate (replacing the photo covers of Volumes 1 & 2) does portray the likeness of actor Patrick Duffy, but otherwise appear to be designed to attract the eye of general sci-fi readers rather than just fans of the recently-cancelled show.
I didn't pick up these last two books in '78 (I wonder if their distribution was less pervasive than the earlier books?), but have added them to my library recently, thanks - in part - to Star Kid "Caeric ArcLight," who kindly sent me a nice copy of #3.