168 CHOEDATA. 



Class IV. Reptilia. 



Cold-blooded Vertebrates breathing by lungs, and possessing scales or 

 scutes. A single occipital condyle, generally two sacral vertebrae, and 

 (in recent forms) ischial and pubic symphyses and separate pelvic bones 

 and nietatarsals. Heart with two auricles and either an imperfectly 

 divided ventricle or perfectly divided one with mixture of blood-streams 

 outside heart ; at least two aortic arches. 



The following groups of Reptiles covered with scales or scutes are 

 grouped together as Lepidosauria (Plagiotremata) . 



Order 1. Lacertilia (Sauria), lizards. Cloacal aperture a transverse 

 slit; a urinary bladder and two eversible copulatory organs. Protero- 

 saurus (Upper Dyas). Telerpeton (biconcave vertebrae, Trias). Gecko 

 and Platydactylus with biconcave vertebras. Iguana. Draco volans. 

 Chamseleo vulgaris. Scincus. Pseudopus Pallassii and Anguis 

 fragilis, blindworm, limbless. Lacerta agilis, L. vivipara. Monitor 

 varanus. Mosasaurus (Chalk). Amphisbsena. Hatteria (Spheno- 

 don), biconcave vertebrae, no copulatory organs. 



Order 2. Pterosauria, Lias to Chalk. Antebrachium and fifth digit 

 of manus greatly elongated. Jaws usually dentigerous. Bones pneumatic. 

 Pterodactylus longirostris. Pteranodon, toothless. 



Order 3. Ophidia, snakes. Limbless, and without urinary bladder. 

 Jaw apparatus with elastic bands. Typhlops, mouth cannot be widely 

 opened. 



Colubriformia: Boa constrictor. Python- Coronella aus- 

 triaca ( = la^vis) smooth viper. Tropidonotus natrix, common snake. 

 Coluber. Dryophis. 



Proteroglypha, poisonous snakes, with grooved fangs in the front 

 of the upper jaw : Naja tripudians, cobra. Hydrophis, Indian Ocean. 



Solenoglyphia, with triangular head, and a poison-fang on either 

 side of the small upper jaw. Pelias (Vipera) berus, adder. Crotalus 

 horridus, rattlesnake. 



