The teeth are, in the adult, planted in separate deep sockets. The skull is very dense and solid, and all the component bones including the quadrate are firmly united. The dorsal surface of the skull is generally characteristically sculptured. There is an interorbital septum, and the orbitosphenoidal and presphenoidal regions are imperfectly ossified. Supratemporal, infratemporal, and post-temporal fossae occur, but no interparietal foramen. In living genera there is a long secondary palate formed by the meeting in the middle line of the palatines, pterygoids and maxillae (fig. 43, A). Cervical ribs (fig. 41, 8 and 9) are well developed, and articulate with rather prominent surfaces borne on the neural arches and centra respectively. The thoracic ribs articulate with the long transverse processes, and sternal ribs and abdominal splint ribs (fig. 46, 4) occur. The sternum is cartilaginous, and both it and the shoulder-girdle are very simple. The precoracoid is represented by merely a small process on the coracoid, while the clavicles are absent, except in the Parasuchia. In the pelvis (fig. 49) there is a large ilium, and an ischium meeting its fellow in a ventral symphysis; these two bones form almost the whole of the acetabulum. In front of the acetabulum, in the Eusuchia, projects a bone which is generally called the pubis, but is in reality rather an epipubis (fig. 49, 4), the true pubis being probably represented by a fourth element which remains cartilaginous for some time, and later on ossifies and attaches itself to the ischium. The limbs are small in proportion to the size of the body, and are adapted for swimming or for shuffling along the ground; they are plantigrade and the bones are all solid. In living forms the anterior limbs have five digits and the posterior four, the fifth being represented only by a short metatarsal. The first three digits in each case are clawed. The calcaneum has a large backwardly-projecting process. The order Crocodilia may be subdivided into two suborders. _Suborder (1)._ PARASUCHIA. The vertebral centra are flat or biconcave. The premaxillae are very large, and the nares are separated, and placed far back. The posterior narial openings lie comparatively far forward between the anterior extremities of the palatines. The palatines and pterygoids do not form a secondary palate. The supratemporal fossae are small, and open posteriorly, the lateral temporal fossae are very large. The parietals and frontals are paired. Clavicles are present. The best known and most important genus of these extinct crocodiles is _Belodon_. _Suborder_ (2). EUSUCHIA.