1. Omosternum narrow and cartilaginous. Metasternum with a bony style ending in a cartilaginous disc. Fingers and toes slightly swollen. Neotropical: .......... Engystomops, p. [168].
2. Omosternum absent. Metasternum cartilaginous.
α. Fingers and toes webbed; terminal phalanges T-shaped and with adhesive broadened tips. Africa and India: .......... Nectophryne, p. [169].
β. Fingers free, toes webbed; terminal phalanges simple, not dilated. Tympanum distinct. Java: .......... Nectes, p. [169].
3. Metasternum cartilaginous, sometimes ossified along the middle. Fingers free; toes more or less webbed; tips simple or dilated into very small discs: .......... Bufo, p. [169].
B. Pupil a vertical slit. The epicoracoid cartilages are narrow and scarcely overlap. Omosternum absent except in Cophophryne. Vomerine teeth absent. Sacral diapophyses strongly dilated. The terminal phalanges are simple and the tips are pointed.
a. Australian. Tympanum distinct. The metasternum is calcified along the middle: .......... Myobatrachus, p. [184].
b. Mexican. Tympanum absent. Metasternum rudimentary: .......... Rhinophrynus, p. [185].
c. Himalayan. Tympanum absent. Metasternum with a slender bony style: .......... Cophophryne sikkimensis.
Engystomops is interesting because it closely resembles the Cystignathoid genus Paludicola, and thereby seems to connect these two families. It differs from Paludicola chiefly by the absence of teeth, by the moderately dilated sacral diapophyses and by the slightly swollen tips of the fingers and toes, the end-phalanges of which are, in one species, E. petersi, T- or anchor-shaped The tympanic disc is either distinct or hidden. The males have a large subgular vocal sac. The generic name refers to the small head with a prominent snout. Three species are known from Central America and Ecuador.