Between the reptiles and the fishes, stretches a wonderful chain of living links by which those two Classes of vertebrates are so closely and unbrokenly united, and by such an array of forms, that they constitute an independent Class, the Batrachia, or Amphibia. In the transition from water to land, from fins and gills to legs and lungs, Nature has made some strange combinations. In some instances the fins, legs, lungs and gills have become so mixed that several notable misfits have resulted, and in some cases we see gills and legs going together, while in other lungs and fins are associated. The Reptile House contains about two dozen species of Amphibians, and it is reasonably certain that this number will be maintained and increased. They are to be found in small aquarium cases, ranged along the south side and eastern end of the Main Hall. The Bullfrog, (_Rana catesbiana_), is a fair representative of the Batrachians which stand nearest to the true land-going reptiles. During the early stages of its existence it is in turn, a fin-tailed tadpole with no legs, a short-tailed tadpole with a pair of front legs, a shorter-tailed tadpole with four legs, and finally a fully-developed, land-going frog with a voice like a small bull, and no tail whatever. Of the genus _Rana_, there are five species in the eastern United States, several of which inhabit the Zoological Park. The Wood Frog, (_Rana sylvatica_), is frequently seen in moist valleys in the Zoological Park, where its chocolate brown back so closely matches the color of the dead leaves and moist earth; it is difficult to find, save when it takes one of its flying leaps. The specimens shown were taken near the Beaver Pond. The Tree Frog, (_Hyla pickeringi_), is the commonest of the queer little tree-loving species which are so easy to hear, and so difficult to find. In spring their voices are the first to be heard in the swamps. The Zoological Park is full of _Hylas_, and their cheerful piping is heard at all seasons, especially in dry midsummer, when dark storm-clouds gather and promise rain. The Common Toad, (_Bufo lentiginosus_), is found in the Zoological Park, though not in such abundance as the two preceding species. Among the most remarkable creatures in the Reptile House are the specimens of Smooth-Clawed Frog, (_Xenopus laevis_), from Africa and The Surinam Toad, (_Pipa americana_). Both of these species are strictly aquatic and have broadly palmated hind feet. The Surinam Toad comes from Dutch Guiana. It is unique in its breeding habits. The male collects the eggs and places them on the female’s back where they are engulfed in large folds of the skin, which form cells in which the metamorphosis occurs.