ORDER VII 



CROCODILIA 



221 



Family 2. Gavialidae. 



Snout produced into a long, narrow rostrum, and passing abruptly into the facial 

 region. Nasals separated from premaxillae by a wide interval. Mandibular 

 symphysis extended. Teeth numerous, approximately uniform, slightly curved 

 acuminate, and finely striated. Tertiary and Recent. 



Gavialis, Oppel (Leptorhynchus, Clift ; Rhamphostoma, Wagler), (Fig. 321). 

 Recent in India and Bnrmah. Fossil in Pliocene of Siwalik Hills, India, 

 where it accompanies the gigantic and closely allied Iihamphosuchus crassidens. 

 Falconer and Cautley (total length 15 m.), and possibly also present in the 

 Eocene of Sussex. 



Leptorhamphus, Oxydontosaurus, Ameghino. Tertiary ; Argentina. 



Family 3. Alligatoridae. 



Snout broad and short. Orbits larger than supratemporal vacuities, and conter- 

 minous with the lateral temporal fossae. Mandibular symphysis short. Teeth 

 irregular; the anterior tooth of lower jaw always, and as a rule also the fourth 

 tooth, fitting into pits of the upper jaw. Suture between maxillae and premaxillae on 

 the palate either transverse or convex toward the front. Dorsal armour consisting of 

 more than two rows of 

 scutes, either articulated 

 together or lying free in 

 the integument ; cervical 

 scutes separated from 

 the dorsal. Ventral 

 armour, when present, 

 comprising n nmerous 

 series of articulated 

 scutes, each of which 

 consists of two pieces 

 united by suture. Upper 

 Cretaceous to Recent. 



In alligators the 

 lower teeth bite en- 

 tirely within the 

 upper, and the first 

 and fourth lower teeth 

 are received into pits 

 of the upper jaw ; but 

 in crocodiles the upper 

 and lower teeth mutu- 

 ally interlock, while 

 the first lower tooth 

 bites into a perfora- 

 tion or pit in the cranium, and the fourth into a lateral notch. Modern 

 alligators inhabit the warmer regions of North America and China, and fossil 

 remains occur in the fresh-water. Cretaceous and Tertiary of both Europe 

 and America. 



Diplocynodon, Pomel (Figs. 319, 325). Third and fourth teeth of lower 



Fig. 3S 



Diplocynodon get vaisi, Aymari 



Oligocene ; Etonzon, near Le Puy, Prance. 

 Superior and palatal aspects of skull, ',■_>. A, Orbit;/, Frontal ; j, Jugal ; la, 

 Lachrymal; mx, Maxilla; N, External nostril; na, Nasal; pa, Parietal; pmx, 

 Premaxilla ; pff, Prefrontal; ptf, Postfrontal ; S, Supratemporal vacuity ; sq, 

 Squamosal. 



