[DallasMike]

How do you know they were based on his drawings and not on actual photos? I have yet to see a creationists who could tell the difference.

Sorry that those of who exercise some healthy skepticism aren't as brilliant as you but I reached my conclusion because the website says:

Page 223 of the Lion Book (BIOLOGY - The Living Science) and page 283 of the Elephant Book (BIOLOGY by Miller and Levine) each contain drawings of the early stages of embryonic development in several vertebrates. Although neither of these drawings are identical to his, they are based on the work of Ernst Haeckel (portrait at left), a 19th century German Biologist who was a pioneer in the study of embryonic development.

[CarolinaGuitarman]

The link also states that Haeckel's theories were not and have not been taught for years. There is nothing wrong with using embryological evidence to support evolution. And, despite what creationists claim, Darwin NEVER used Haeckel's drawings, nor his arguments, to bolster evolution. Simply stated, creationists bring up Haeckel as a strawman because they lack legitimate means to deal with evolution.