This is a Christmas card found in an English scrapbook preserving the years 1870-1880. The text around whatever it is riding the black porker reads “A Dead Heat for the Plate.” So, as far as I can tell, you have two hogs racing for my oven, one carrying a turkey on its back and one carrying what looks like nothing I’ve ever seen.
You thought they didn’t do humourous cards back then, didn’t you?
Don’t ask me to explain the joke to you. The best I can do is point out that it’s British humour, which might be all the explanation there is.
But surely there must be more. What’s your explanation?