This is not a mistake in numbering, and you haven't missed the posting of the first 3 parts! I simply finished this one first, and since it can be useful even in the absence of the primer, it would have made no sense to keep it in the fridge till they're all done. It will of course be even more useful in the light of the generalities, so don't point that out, as this is the plan for this tutorial series:
PART 1: Cat anatomy and details
PART 2: The cat in motion
PART 3: Big cat species
PART 4: Little cat species
(PART 5: Wild Cat and Domestic Cat races – not sure about this one yet, depends if I'm thoroughly sick of cats by then!)

All the Little Cats (Felinae) species are shown here, save for a couple listed at the top of the document (no subspecies!) Even though it is completely irrelevant for an illustrator whether the Bay Cat goes under Catopuma or Pardofelis, I've done my best to abide by the latest classification system, but let me tell you it's not particularly easy to find out which is the latest to start with. If there are errors in that regard please let me know, but only if you're somehow involved with taxonomy and absolutely certain – I don't want to have to make repeated changes. Yes, this one alone took weeks.

My sources will be listed when this thing is complete.

For the rest of my tutorials go here.
For my tutorial books go here.