The primate in question bares its fangs in a grotesque parody of a grin, an oddly intelligent look in its eyes as it regards Jamie and the Doctor. There's a disturbing hunger there, as well, as if it's just been presented with something wonderful to eat. The only question is - who does it want first?

The one in the skirt looks younger, but masculine and therefore stronger. The noisy book-stealer, on the other hand, is clearly female and weaker...and not only still talking, but gesturing as if she actually wants to be eaten.

Obviously, the monkey will just have oblige the Doctor on that score. It roars and charges straight at her.