sticking to the tongue, it is with marvelous rapidity whipped back to the frog's throat and swallowed. Frogs will also seize some of their prey in other ways, and for this purpose they use their jaws and teeth, which latter are to be found on the palate and upper jaw. I have frequently taken them with hook and line, the former being baited only with a small piece of red flannel. So far as I know at present there is no species of frog that has come to the knowledge of science that possesses a poison gland or apparatus. Some of them, however, secrete from their skin pungent and disagreeable secretions. These are protective in a way, and prevent other animals from preying upon them. In a species of Hyla I met with upon the island of Cuba this secretion was so strong as to bring water to the eyes, and upon one occasion when handling one of these creatures and then rubbing my eyes the lids of the latter swelled tremendously, and this condition was only reduced after proper treatment lasting over three or four days. There is another tree frog (Hyla micans) in which this secretion of the body is slimy and profuse, and it at the same time possesses luminous properties, which probably also serves to protect the animal from its enemies. There are many beautiful examples of protective mimicry to be seen among frogs, especially among the brown or the green tree frogs, or other arboreal forms that are mottled and shaded with greens, grays, and browns. These species usually feed at night and are still all day, being detected only with difficulty, as they rest upon leaves, limbs, or rocks. Some are brilliantly colored, but they are nonedible varieties, and so their high-colored skins serve them as a protection.
Fossil frogs first occur in the Tertiary, but they become more abundant in the Miocene period.
The region of the delta of the Yukon is described by W. H. Dall, in his paper on Alaska as it Was and Is, as remarkable for being the breeding place of myriads of waterfowl, some of which are peculiar to the Alaskan region. Nearly a hundred species gather there, and one of them comes all the way from north Australia, by the coasts of China and Japan, to lay its eggs and rear its young in this spot.