I can't help wonder what the heck this thing might have been. An exotic creature merely unknown to Londoners? A ghastly mutation resulting from DNA gone mad? The product of a fiendish attempt at cross-breeding?
Of course we don't know for sure if the story is even true. There may be good reason why the tale carries the disclaimer "legend." It seems to me that if such a creature really did cause such a stink in London that someone would have attempted to illustrate it for a newspaper or magazine. (Photography was around, but photos in those days required long exposures, and perhaps the monster couldn't sit still long enough.) I have done an Internet search for an illustration of the beast without success. I'd love to see what it looked like.
Also see: Monsters from the Shadows of Reality | Monsters, Monsters Everywhere


Comments
I would say from Charles Fort’s description is was a tame pig that was born deformed. The back end and the head and the hair all looked like a boar’s and pigs do definitely make shrieking noises.
Late last year, a horribly deformeed pig was born in China. It had a face resembling a cross between a monkey and a gargoyle and had a body remnicent of some hopping animal, like a kangaroo or rabbit. My daughter set it as the desktop wallpaper on our home computer as a cruel joke. I’m too lazy to google the story (or maybe I just don’t want to see that photo again), but I wouldn’t be surprised if Mr. Davy’s monster is a pig born with this sort of deformity. It was truly scary. When I saw it, I said “Kiiilll meeee….I shouldn’t beeeeee….” and dubbed it ManBearPig.
Here it is:
http://xenophilius.wordpress.com/2008/07/26/piglet-with-monkeys-face/