EUSUCHIA. DINOSAURIA. 383 



within the pterygoids ; maxillae, palatines, and pterygoids with palatal 

 plates. Littoral and marine deposits of the Upper Cretaceous of Europe 

 and North America to present clay. Thoracosaurus Leidy, Upper Ore- 



on_9~l 



taceous of N. Amer. and France ; Tomistoma Miiller, -^-^ teeth on each 

 side ; nasals in contact with premaxillaries, separate from nasal aperture ; 

 living in Borneo, fossil in Tertiaries of Europe. Gavialis Oppel, 2 _~" 



teeth on each side ; nasals separated from premaxillaries and from nasal 

 aperture ; without ventral bony scutes ; living in India and Burma, fossil 

 in the Pliocene of the Sivalik Hills ; G. gangeticus Gray, N. India, Bom- 

 bay, Aracan ; harmless, and living on fish, to 20 feet. Rhamphosuchus 

 from the Pliocene of the Sivalik Hills, to 50 feet. 



Fam. 7. Crocodilidae. Vertebrae procoelous, nares anterior, nasals 

 almost always reaching nasal aperture ; choanae far back surrounded by 

 the pterygoids ; maxillaries, palatines, and pterygoids with palatal plates ; 

 orbit communicating with the infra-temporal fossa ; ribs with uncinate 

 processes ; clavicles absent ; pubis excluded from the acetabulum ; 

 5 fingers, 4 toes ; dorsal armour ; pupil vertical. From the Upper Cre- 

 taceous to the present day, found in Europe until the Pleistocene. Diplo- 

 cynodon Pomel, extinct, Oligocene and Miocene of Europe ; Bottosaurus 

 Ag., Upper Cretaceous of North America. Crocodilus, Laur., 

 head long, teeth unequal, fourth mandibular tooth usually fitting into a 



notch in the upper jaws, -* - teeth on each side, without bony nasal 

 l- 15 



septum, without ventral armour ; Afr., S. Asia, N. Australia, trop. 

 Amer., from the Upper Cretaceous to the Pleistocene in Eur. Osteolaemus 

 Cope, fourth mandibular tooth as in the last, nasal bones dividing the nasal 

 aperture, ventral scutes bony, W. Afr. one species. Alligator Cuv., head 

 short and broad ; teeth very unequal, fourth mandibular tooth fits into 

 a pit of the upper jaw ; jsris teeth on each side ; nasal bones dividing 



nasal aperture ; dorsal bony scutes not articulated together, ventral scutes 

 without or with thin ossifications ; two living species, one in China, and 

 the other in N. Amer. ; from fluviatile deposits of Upper Cretaceous to 

 Pliocene in Eur. Caiman Spix (Jacare Gray), head, teeth, and fourth 

 mandibular tooth, as in the last, -.g^Hn teeth on each side, without bony 

 nasal septum, with dorsal and ventral armour of articulated bony scutes, 

 5 species, Central and South Amer. 



Sub-class 4. DINOSAURIA.* 



Long-tailed reptiles usually of considerable, often of gigantic size, with a 

 superior and inferior temporal arcade, a fixed quadrate, and thecodont den- 

 tition ; without pineal foramen. The limbs are adapted for the habitual 

 support of the body, the ilium is extended antero-posteriorly, and the pelvis 

 and hind limbs are generally bird-like in structure. The ribs are two-headed. 



The Dinosauria make their appearance in the Trias and persist until the 

 Cretaceous. Their remains have been found in Europe, Asia, S. Africa, 

 Madagascar, N. and S. America, and in Australia. It has been suggested 

 that they were amphibious. This suggestion is based on the large size of 



* Also called the Ornithoscelida. 



