a. Fourth mandibular tooth fitting into a notch in the upper jaw.
1. Without a bony nasal septum .......... Crocodilus, p. [454].
2. Nasal bones dividing the nasal groove .......... Osteolaemus, p. [466].
b. Fourth mandibular tooth fitting into a pit in the upper jaw.
1. Without a bony nasal septum .......... Caiman, p. [471].
2. Nasal bones dividing the nasal groove .......... Alligator, p. [466].
Fam. 1. Teleosauridae, in the Lias and Oolite of Europe; marine.–Snout very long and slender. Nasals widely separated from the premaxillae by the maxillaries. Choanae at the posterior end of the palatines. In front of the eye a small sub-lacrymal foramen. Supratemporal foramina large. Vertebrae amphicoelous. Anterior limbs scarcely half as long as the posterior pair. The dermal armour consists of two rows of broad scutes on the back, while the belly is protected by a shield of numerous bony scutes, which are connected with each other by sutures. Teeth numerous and rather slender. General appearance like that of Gavials.
Teleosaurus of the Middle and Upper Oolite in England and France. Snout very slender. Nasals narrow and short. The under side is protected by a beautifully finished armour, consisting of a square breast-shield of four rows of bony scutes, and a larger, long, oval shield on the belly, with about six longitudinal and seventeen transverse rows of scutes.
Mystriosaurus, of the Upper Lias in France and Germany, reached a length of 15 feet, and is characterised by an additional series of keeled but smaller caudal plates running parallel with the middle pairs, which are neatly sutured together.
Fam. 2. Metriorhynchidae, in the Upper Oolite of Europe; marine.–Nasals broad posteriorly, sometimes extending with a pointed wedge very near the premaxillae. Without sub-lacrymal foramina. Eyes with a ring of ossifications in the sclerotic. Dermal armour unknown. Vertebrae and choanae like those of the previous family. Metriorhynchus and Geosaurus.