Damn, that ended up being a bit of a rabbit hole.

The source for this image was Wikimedia Commons which describes them as "Romanes' 1892 copy of Ernst Haeckel's fraudulent embryo drawings."

I hadn't heard of these fraudulent drawings that were seemingly so notorious that describing them as fraudulent needed no further elaboration, so I went on Ernst Haeckel's Wikipedia page which has a longish subsection about these specific drawings. Apparently some... shall we say artistic license, was taken to make the different embryos look more similar to one another, and by modern standards they're useful mostly for getting the idea across but are not completely true to life.

Wikipedia even has an article specifically about embryo drawings. The short of this story seems to be that there was some controversy back in Haeckel's day mostly by people who rejected Darwinism. In the 90s some scientists noticed that these drawings didn't match what they see in the lab and wrote a paper about it. Their paper was hijacked by people who reject Darwinism (i.e. creationist nutsos) and so there was more controversy than the matter probably really deserved.

Finally, I found this article on the website of the National Center for Science Education that defends Haeckel's drawings, comparing them to modern photographs with any egg yolk removed (as the embryos were originally depicted without the yolk, something Haeckel was up front about) to show that they weren't that inaccurate: