I have never seen men so wrapped up before, and women so only in the East. They wore turbans, too, and thereunder peered out their elfin faces at me, faces with protruding lower jaws and bright eyes. (6.5)
As superficial as it may be, we identify people by the clothes they wear. Let's just admit it; we all do it. Prendick first notices the difference in the Beast Folk's clothes before working his way to the physical differences.
This man was of a moderate size, and with a black n****id face. (6.6)
Prendick attempts to identify the Beast Folk by connecting them with something distinctly non-European. By today's standards it comes across on the wrong side of racist. For Victorian readers however, it would have given the Beast Folk and the island an air of mystery, since Africa and African cultures were far from understood—though still easily exploitable.
Each of these creatures, despite its human form, had woven into it, into its movements, into the expression of its countenance, into its whole presence, some now irresistible suggestion of a hog, a swinish taint, the unmistakable mark of the beast. (9.10)
Prendick finally notices the animal aspects of the Beast Folk's identity. It's like when you finally see the hidden picture within another picture. Once you see it, you can't un-see it.
There was no mistake this time in the quality of the dim broken sounds, no doubt at all of their source; for it was groaning, broken by sobs and gasps of anguish. It was no brute this time. It was a human being in torment! (10.20)
Prendick can connect with the pain and anguish of the puma, and the connection causes him to identify with the puma. Do you think he'd identify just as easily with the puma if he didn't mistake it for a human?
Superficially the contagion of these brute men was upon me, but deep down within me laughter and disgust struggled together. (12.19)
Outer identity and inner identity are not always the same thing. Take this example: on the outside, Prendick becomes one of the Beast Folk by joining in their ceremony. Inside, he's laughing his butt off. Judge not though—we've all been there, right? Feeling one thing while pretending to feel another?
The men aboard ship, [Montgomery] told me, seemed at first just as strange to him as the Beast Men seemed to me,—unnaturally long in the leg, flat in the face, prominent in the forehead, suspicious, dangerous, and coldhearted. (15.10)
Montgomery points out that, sometimes, humans can't identify with each other because of our physical and social differences. This inability to identify causes Montgomery to feel as much of a disconnect towards parts of humanity as Prendick feels towards the Beast Folk society.
When I saw their wincing attitudes and the furtive dread in their bright eyes, I wondered that I had ever believed them to be men. (16.56)
When Prendick sees the Beast Folk cower, he decides they're even less human than he previously thought. Because real people don't cry. It's true. We're pretty sure there's even a song about it; it's that true.
It may seem a strange contradiction in me—I cannot explain the fact—but now, seeing the creature there in a perfectly animal attitude, with the light gleaming in its eyes, and its imperfectly human face distorted with terror, I realised again the fact of its humanity. (16.84)
It seems Prendick flip-flopped since quote #7. After killing the Leopard Man, Prendick has had a change of heart. Better late than never, unless you're considering things from the Leopard Man's perspective. Kinda ironic though that it's the Leopard Man's very animality that makes Prendick realize his humanity...
"None escape," I said. "Therefore hear and do as I command." They stood up, looking questioningly at one another. (20.7)
Prendick tries to identify himself as the new ruling member of beast society. No dice. The Beast Folk have already seen him do too many un-Moreau-y things to buy it.
I, too, must have undergone strange changes. My clothes hung about me as yellow rags, through whose rents glowed the tanned skin. My hair grew long, and became matted together. I am told that even now my eyes have a strange brightness, a swift alertness of movement. (21.42)
Prendick changes into a member of the Beast Folk! All the identity markers are there: the clothes, physical appearance, and habits. He's Survivor-ready.