Thus amongst vertebrates it is considered certain that Birds and Reptiles are branches of the same stock,-and, still farther on, that at least all placental mammals-bats and whales, elephants and mice-trace their pedigree to some common progenitor.
"The Old Riddle and the Newest Answer"
John Gerard
Yet the placental secretion must not be looked upon as something wholly evil in its potentialities.
"The Glands Regulating Personality"
Louis Berman, M.D.
A recent insectivorous placental mammal, from Sumatra.
"The Student's Elements of Geology"
Sir Charles Lyell