There is a certain type of illustration, that I typically associate with old storybook illustrations, where the illustration has been cropped into an oval shape. I've attached some examples here one from some old childrens book that I don't know the name of, and the other from Alice in Wonderland.
I'm wondering if there is a specific name for this practice/type of image since I would like to find more examples and information about it (i.e. was there a technical reason why it was done, is it simply a style choice etc.). For this question I'm primarily interested in the name of the practice if there is one.