> The guinea pig is not known as a smart or reliable steed, nor even a terribly fast one, although they can put on a good scrambling turn of speed when panicked (often into walls, while uttering a frantic "WHEEP! WHEEP!" as they go.) But they're cute and good-natured and exceedingly docile, and they utter a charming purr when happy, so people insist on thinking they're a good mount for the elderly and infirm. This has led to the regrettably common sight in many cities--first the distant piercing "WHEEP! WHEEP!" and the thin screams of the invalid tied to it, then the scrabbling gallop of th…