The quadrate bears the knob, and the angular the cup for the articulation of the mandible,—a very primitive feature. The mandible is also noticeable for the enormous backward projection of the angular.
Anura. In Anura the skull is very short and wide owing to the transverse position of the suspensorium. There is often a small ossification representing the quadrate. Sometimes as in Hyla and Alytes there is a fronto-parietal fontanelle.
As compared with the skull in Urodela the chief characteristics of the skull of Anura are:—
1. the presence of a sphenethmoid,
2. the union of the frontals and parietals on each side,
3. the occasional occurrence of small supra- and basi-occipitals,
4. the backward growth of the maxillae and its connection with the suspensorium by means of the quadratojugal,
5. the dagger-like shape of the parasphenoid,