to prove the existence of a generic animal, "or in other terms, proving hereditary descent to have a relation primarily to genus or natural family". This way, he could lay claim to a stability in the natural order at the level of the genus, but let species be extinguished. Man was a genus; not a species. Evolution According to Richards, The Races of Men advocated "a common material origin of life and its evolution by a process of saltatory descent"; that is to say, new species arose not by gradual change but by sudden leaps due to shifts in embryonic development. Knox tentatively concluded that "simple animals ... may have produced by continuous generation the more complex animals of after ages . . . the fish of the early world may have produced reptiles, then again birds and quadrupeds; lastly, man himself?" Newly formed species survived or perished according to external conditions, which acted as "potent checks to an infinite variety of forms". For one contemporary reviewer, his claim that "Species is the product of external circumstances, acting through millions of years" was "bold, disgusting, and gratuitous atheism." In modern terms, he proposed a theory of saltatory evolution, in which "deformations" in embryonic development produced "hopeful monsters" that, if fortuitously suited to the prevailing environmental conditions, gave rise to new species in a single, macroevolutionary leap. In 1857 he wrote: "The conversion of one of these species into another cannot be so difficult a matter with Nature, especially when all or most of the specific characters are already present in the young. Thus a given species may perish, but another of the same consanguinité takes its place in space: it is a question of time... Thus parenté extends from species to genus and from genus to class and order, in characters not to be misunderstood." Legacy Knox is commemorated in the scientific name of a species of African lizard, Meroles knoxii. Knox in fiction An Amazon original anthology television series Lore features Burke and Hare murders case in its Season 2 episode 1 named " Burke and Hare: In the Name of Science" released on October 19, 2018. Peter Cushing plays Knox in The Flesh and the Fiends (1960). Written and directed by John Gilling, the film is a reasonably accurate depiction, allowing for some dramatic licence and time constraints, of the Burke and Hare story. The Anatomist (1961), a