pinktentacle.com had a post about the Kaikidan Ekotoba, a kind of Monsters Manual from 19th century Japan. One of the illustrations is of a seal, which can be quite nasty. The picture shows it is rather menacing. Coincidentally I had been researching Moche watercraft from the 2nd to 6th century AD or so and found this illustration from a different blog, Echoes of a Mesa. Based on a painted pot, and part of a display at the MNAAHP, it shows an altogether different type of seal, a ridiculously happy one.
Thanks for Kristin for putting 2 and 2 together!