Coming down to our own era, and the time when travel and education first induced the observation and study of animals with a view to learn their habits, and to arrange them under some system of classification, we begin to see the perplexities that presented themselves to naturalists, especially with regard to egg-producing creatures. To Topsell, a writer of the seventeenth century, every creeping or crawling thing was ‘a Serpente,’ and many insects were included in his category. To Lawson, on the contrary, every egg-producing creature, if not a bird, was an ‘Insect.’ In his _History of Carolina_, 1709, he describes, under ‘Insects of Carolina,’ all the snakes he saw, also the alligators, lizards, etc., and thus continues: ‘The Reptiles or smaller Insects are too numerous to relate here, the Country affording innumerable quantities thereof; as the Flying Stags with Horns, Beetles, Butterflies, Grasshoppers, Locusts, and several hundred of uncouth Shapes.’ Having thus gone through the ‘Insects,’ except the ‘Eel-snake’ (which turns out to be a ‘Loach’ or _leech_), he gets puzzled over a ‘Tortois, vulgarly called Turtle, which I have ranked among the Insects, because they lay Eggs, and I did not know well where to put them.’ And Lawson was not alone in not knowing ‘where to put’ a countless number of other creatures that go to form the endless links in the long chain of living organisms; even plants, which, to use Darwin’s words, ‘with animals, though most remote in the scale of nature, are bound together by a web of complex relations.’ You may place the dove at one end of the chain and the crocodile at the other, without one broken link. The earliest bird which palæontology has revealed had teeth in its bill, claws on the end of its wings, and a long tail with feathers growing out of it, like a pinnate leaf.