1. premaxillae.for the trigeminal nerve.16. maxillae.25. squamosal.
2. nasal.8. opisthotic.17. palatine.26. jugal.
3. frontal.9. basi-occipital.18. dentary.27. external mandibular
4. parietal.10. quadrate.19. splenial.foramen.
5. supra-occipital.11. pterygoid.20. angular.28. internal mandibular
6. epi-otic.12. basisphenoid.21. supra-angular.foramen.
7. pro-otic.13. alisphenoid.22. articular.VIII. internal auditory
immediately in front of the14. prefrontal.23. coronoid.meatus.
figure 7 is the prominent foramen15. vomer.24. exoccipital.XII. hypoglossal foramen.

The maxillae (figs. 43, A, 2 and 44, 2) are a pair of very large bones and bear the remaining teeth of the upper jaw, set in sockets along their alveolar borders. On the dorsal side each maxillae is continuous with the premaxillae, nasal, lachrymal, and jugal, while ventrally it meets its fellow in a long straight suture and forms the greater part of the long bony palate. The maxillae are separated in the middle line posteriorly by processes from the palatines, while further back they meet the transpalatines. The internal or nasal surface, like that of the premaxillae, is excavated by a deep longitudinal groove, the narial passage. In a ventral view of the skull a number of small openings (fig. 43, A, 21) are seen close to the alveolar border, these are the openings of small vascular canals which lead into the alveolar sinus, a passage traversing the maxillae, and transmitting the superior maxillary branch of the trigeminal nerve and certain blood-vessels. This alveolar sinus opens posteriorly by the more external of the two large holes in the maxillae, which lie close to the anterior edge of the posterior palatine vacuity, to be described immediately. The more internal of these holes, on the other hand, leads into a cavity lodging the nasal sac. Behind the maxillae the completeness of the palate is broken up by the large oval posterior palatine vacuities (fig. 43, A, 7); these are separated from one another in the middle line by the palatines, and are bounded elsewhere by the maxillae, transpalatines, and pterygoids.

The palatines (fig. 43, A, 3) are long and rather narrow bones interposed between the maxillae in front and pterygoids behind. They meet one another in a long suture and form much of the posterior part of the palate, while the whole length of their dorsal surface contributes to the floor of the narial passage. The dorsal surface of each bone is also drawn out on its outer side into a prominent ridge which forms much of the side and roof of the narial passage, being in contact with the vomer and pterygoid, and at one point by means of a short ascending process with the descending process of the prefrontal.

The pterygoids (figs. 43, A, 4, and 45, 11) are a pair of large bones, each consisting of a median more or less vertical part, which becomes ankylosed to its fellow in the middle line early in life, and of a wide horizontal part which meets the transpalatine. They completely surround the posterior nares (fig. 43, A, 5) and their median portions form the whole boundary of the posterior part of the narial passage, and assist the palatines and vomers in bounding the middle part. The horizontal parts form the posterior part of the secondary palate, while the dorsal surface of each looks into the pterygoid fossa, a large cavity lying below the quadrate and quadratojugal at the side of the skull. The lateral margin adjoining the transpalatine is in the fresh skull terminated by a plate of cartilage against which the mandible plays. Dorsally the pterygoid articulates with the basisphenoid, quadrate, and alisphenoid.

The transpalatines (fig. 44, 11) connect the pterygoids with the jugals and maxillae, articulating with each of the three bones by a long pointed process. The jugal process meets also a down-growth from the postfrontal.

The jugals or malars (fig. 44, 5) are long somewhat flattened bones which are united to the lachrymals and maxillae in front, while passing backwards each is united behind to the quadratojugal (fig. 44, 12), the two forming the infratemporal arcade which constitutes the external boundary of the orbit and lateral temporal fossa. The jugal is united below to the transpalatine, and the two bones together form an outgrowth, which meeting that from the postfrontal forms the postorbital bar, and separates the orbit from the lateral temporal fossa. The quadratojugals are small bones and are united behind with the quadrates.

The quadrate (figs. 43, A, 13 and 44, 8) of each side is a large somewhat flattened bone firmly fixed in among the other bones of the skull. It is terminated posteriorly by an elongated slightly convex surface, coated with cartilage in the fresh skull, by which the mandible articulates with the cranium. The dorsal surface of the quadrate is flat behind, further forwards it becomes much roughened and articulates with the exoccipital and squamosal; further forwards still it becomes marked by a deep groove which forms the floor of the external auditory meatus and part of the tympanic cavity. The anterior boundary of the quadrate is extremely irregular, it is united dorsally with the postfrontal, pro-otic, and squamosal, and more ventrally with the alisphenoid. The smooth ventral surface looks into the pterygoid fossa. In front the quadrate forms the posterior boundary of the supratemporal fossa and foramen ovale, and is continuous with the alisphenoid, while it sends down a thin plate meeting the pterygoid and basisphenoid. On the inner side of the dorsal surface of the quadrate near the condyle, is a small foramen which leads into a tube communicating with the tympanic cavity, by a foramen lying in front of and ventral to that for the exit of the facial nerve. By this tube air can pass from the tympanic cavity into the articular bone of the mandible.

The squamosal (fig. 44, 7) meets the quadrate and exoccipital below, and forms part of the roof of the external auditory meatus, while above it forms part of the roof of the skull and has a pitted structure like that of the other bones of the roof. It is continuous with the postfrontal in front, forming with it the supratemporal arcade which constitutes the outer boundary of the supratemporal fossa. It meets also the parietal on its inner side, forming the post-temporal bar, the posterior boundary of the supratemporal fossa.

It may be useful to recapitulate the large vacuities in the surface of the Crocodile's cranium.