Fam. 2. Pelobatidae.–The upper jaw and, as a rule, the vomers are provided with teeth. The tongue is oval, slightly nicked, and free behind, so that it can be thrown out, except in Asterophrys turpicola of New Guinea, which has a large but entirely adherent tongue. The vertebrae are procoelous, except in Asterophrys and the Malay genus Megalophrys, where they are opisthocoelous. The sacral diapophyses are strongly dilated. The omosternum is small and cartilaginous. The metasternum has a bony style, and ends in a cartilaginous, rounded or heart-shaped disc, but in Scaphiopus it forms an entirely cartilaginous plate. The tympanic disc is mostly hidden or indistinct, and is quite absent in Pelobates. The Eustachian tubes are very small in Pelobates, and exceedingly minute in Scaphiopus stagnalis of New Mexico. The pupil is vertical. This family contains seven genera with about twenty species, with a rather scattered distribution.
Fig. 32.–Map showing distribution of Cystignathidae, Discoglossidae, and Pelobatidae.
A. Toes extensively webbed, sacrum and coccyx confluent.
a. Metasternum a cartilaginous plate. America .......... Scaphiopus, p. [164].
b. Metasternum with a bony style. Europe .......... Pelobates, p. [162].
B. Toes nearly free. Metasternum with a bony style.
a. Vertebrae procoelous.
α. Sacral vertebra articulating by one condyle with the coccyx.
Europe .......... Pelodytes, p. [165].