x TELEOSAURIDAE GAVIALIDAE 451 



Telcosaurus 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. 



Fam. 3. Macrorhynchidae, in the freshwater deposits of the 

 1'urbeck, Wealden, and Greensand of Europe. Snout long and 

 slender. The nasals are narrow, and so elongated that they 

 meet a similar long extension of the premaxillaries. Choanae 

 between the palatines and pterygoids. Vertebrae amphicoelous. 

 Dermal armour consisting of two imbricating dorsal and eight 

 ventral rows, e.g. Pholidosaurus of the English Wealden. 



Fam. 4. Gavialidae. Snout long and slender. The choanae 

 are situated entirely within the pterygoids. Vertebrae pro- 

 coelous. Members of this family make their first appearance 

 in the littoral marine deposits of the Upper Chalk of Europe and 

 North America ; others are common in tertiary, marine, and 

 freshwater deposits, whilst only two genera and species occur 

 now in the Oriental sub-region. 



Thoracosaurus in the Upper Chalk of New Jersey and France 

 and Belgium is intermediate between Gavialis and Tomistnmn. 

 The prefrontal bones are very small, while the lacrymals are 

 very long and surround the nasals posteriorly. The nasals them- 

 selves are slender, and reach the posterior likewise long and 

 narrow prolongations of the premaxillaries. 



Gavialis. The snout is extremely long and slender. The 

 mandibular symphysis is so long that it comprises a great 

 portion of the splenial bones, and extends backwards almost to 

 the level of the last teeth and to the palatal foramina. The nasal 



