(3) the skeleton of the =jaws and hyoid apparatus=. The skull is much flattened and expanded, though not so much as in the frog. (1) THE CRANIUM PROPER. The =cranium proper= or =brain case= is an unsegmented tube which remains partly cartilaginous, and is partly converted into cartilage bone, partly sheathed by membrane bone. The roof and floor of the cartilaginous cranium are, as is the case also in the frog, pierced by holes or fontanelles, and these are so large that the main part of the roof and floor comes to be formed by membrane bone. Two pairs of large ossifications take place in the cranial walls. Of these the more posterior on each side represents the =exoccipital= and all three =periotic= bones. It bears a small convex patch of cartilage for articulation with the atlas, and with its fellow forms the boundary of the foramen magnum. Two foramina pierce the exoccipital just in front of the occipital condyle and transmit respectively the glossopharyngeal and pneumogastric (fig. 21, X) nerves. Lying laterally to these nerve openings is seen a patch of cartilage, the =stapes=, which is homologous with the stapes or proximal element of the columellar chain in the frog. Further forward in front of the stapes is the small opening for the exit of the facial nerve, and seen in a lateral view close to the orbitosphenoid, that for the trigeminal (fig. 21, C, 5). In front of these large bones the lateral parts of the cranial walls remain cartilaginous for a short distance, and then there follow two elongated bones, the =orbitosphenoids= (fig. 21, B and C, 11), pierced by the foramina for the exit of the optic nerves. These bones partly correspond to the sphenethmoid of the frog. The _membrane bones_ connected with the cranium are the _parietals_, _frontals_ and _prefronto-lachrymals_ on the dorsal surface, and the _parasphenoid_ on the ventral surface. The _parietals_ (fig. 21, A and C, 6) roof over the posterior part of the great dorsal fontanelle and overlap the exoccipito-periotics. They meet one another along a sinuous suture in the middle line, as do also the _frontals_ which overlap them in front. The _frontals_ and _parietals_ both extend for a short distance down the sides of the cranium and meet the orbitosphenoids. The _prefronto-lachrymals_ (fig. 21, A and C, 7) connect the frontals with the maxillae. [Illustration FIG. 21. A DORSAL, B VENTRAL, AND C LATERAL VIEWS OF THE SKULL OF A NEWT (_Molge cristata_) × 2-1/2 (after PARKER). The cartilage is dotted, the cartilage bones are marked with dots and dashes, the membrane bones are left white.