A large blotched ensatina ("Ensatina eschscholtzii klauberi", top) and a Monterey ensatina ("E. e. eschscholtzii", below), populations of the same species that do not interbreed, but grade into other populations of the same species, forming a ring species. From the files Ensatina eschscholtzii klauberi.jpg and Ensatina eschscholtzii e.jpg, both public domain files.