Yeah, that's the way it is on the HuCard. I believe each "tier" has it's own boss that is common to all the levels in said tier.
On the CD version you actually get a different boss for each Zone.
If I'm not mistaken Electric Fan is the boss for Zone B and C on the HuCard. Electric Fan is by far the easiest boss in the game. All you have to do is evade his laser beams, which is incredibly easy, since they do not home in on you. The other anchor-like things he spews at you are a joke and flail under the power of your gun.
You should have the triple-shotgun by this point, so a couple passes over his "head" and Electric Fan has been unplugged.
Ta for that - I turned King Fossil A into a real fossil after that advice.
Heh. The whimsical boss names in Darius are often inspirational of humorous (not to mention offensive and juvenile) nick names when I play through. Some are so good to begin with they need no mockery (eg, Fatty Glutton).
Sending King Fossil the way of the dinosaurs has become so routine he's fondly known as the King Pussy in my camp. The sinister music that accompanies his appearance makes his easy dispatch all the more enjoyable.