Lizards and toads are conspicuous in the more desert areas.
The larynx, which is rudimentary in most of the Caudata and in the Apoda, is highly developed in the Ecaudata, and becomes the instrument of the powerful voice with which many of the frogs and toads are provided.
The tree-frogs, Hylidae, with which the arboreal Ranidae were formerly grouped, show in their anatomical structure a close resemblance to the toads, Bufonidae, and are therefore placed far away from the true frogs, however great the superficial resemblance between them.
Frogs and toads occur wherever insect food is procurable, and their distribution is a world-wide one, with the exception of many islands.
The former type is exemplified by the toads and the lower Ecaudata, whilst the latter is characteristic of the true frogs (Ranidae), although when quite young these batrachians present a condition similar to that which persists throughout life in their lower relatives.