Possible Clues:

• Creatures which increase -- but don't multiply?
• In sum they're long and dangerous
• Abacus users
• Milk snakes, e.g.
• Sound as if they make some danger at length
• Totters, being legless
• Do they put more on with poison?
• Reads about five hundred to make them footless
• Can they totter without feet?
• Perhaps it's summers that has them footless