Silurian variant (Supremacy of the Cybermen)
One type of Silurians seen on prehistoric Earth resembled the caste to which Vastra was native, but were distinguished in that they had only two eyes, no external ears, five digits on each hand, crests on their heads and down their neck, and faces with bulging black eyes, wide curved mouths, and no visible noses. (COMIC: Supremacy of the Cybermen [+]Loading...["Supremacy of the Cybermen (comic story)"])
As such, their genuine faces resembled the Silurian Masks (GAME: Exodus of the Silurians [+]Loading...["Exodus of the Silurians (video game)"]) of their more human-like counterparts, (TV: The Hungry Earth [+]Loading...["The Hungry Earth (TV story)"], etc.)
In an alternate timeline, these Silurians were converted into Cyber-Silurians. (COMIC: Supremacy of the Cybermen [+]Loading...["Supremacy of the Cybermen (comic story)"])