A canonical list of Dr. Seuss's conjoined characters: Additions welcome!
I. Naturally conjoined
•“Lads with the Siamese Beard” (PM (1941)).
•“a long, twisting eel” (McElligot’s Pool (1947)).
•“a very odd family of deer” (If I Ran the Zoo (1950)).
•Whitney and Judson (The 5,000 Fingers of Dr. T (1953)).
•detail from a circus parade (If I Ran the Circus (1956)).
•“When Better Horses Are Breeded, Broder will Brood them” (original sketch (1956)).
•the Brothers Ba-zoo (Did I Ever Tell You How Lucky You Are? (1973)).
•detail from wackiness (Wacky Wednesday (1974)).1
II. Habitually conjoined
Interpreted loosely, every stack of creatures, every pouched kangaroo, or Thidwick might count here, but I am looking specifically at creatures whose identity requires them to exist in conjunction with others.
•“a new sort of hen” (If I Ran the Zoo (1950)).
•To-and-Fro Marchers (If I Ran the Circus (1956)).
•Through-Horns-Jumping-Deer (If I Ran the Circus (1956)).
•”The Economic Situation Clarified” (New York Times Magazine (1975).2
•you, etc. (Oh, the Places You'll Go! (1990)).
III. Do these count?
•“The Facts of Life” (Judge (1934)).
•Liberators of America (PM (1941))?
Art by the great George Booth.
The NYT Magazine ran the image, cropped, with a poem in the middle of it, looking something like this:
This image, and the information concerning it, comes from the excellent book The Zaks and Other Lost Stories (2022).