Class Reptilia
Phylum Chordata
The Reptiles (Class Reptilia) include turtles, snakes, alligators, and lizards.
Though variation exists in reptiles, there are a few physical traits that unite them.
1) Most reptiles lay eggs (oviparous), though some can give birth to live young.
2) Unlike amphibians, their eggs are laid on land and have a leathery shell to protect them from drying out.
3) Reptiles are covered with tough, dry skin and protective scales or plates.
4) Reptiles are cold-blooded. This means that their body temperature is regulated by the temperature around them. If the air temperature is not warm enough they may seek out direct sunlight to raise their body temperature. Because of this, they will spend the winter months in colder climates in torpor, buried in the mud or leaf litter. High temperatures are not good for reptiles either. In a very hot climate they may hibernate during the hottest time as well. This is called estivation.
5) Unlike mammals, reptile teeth are usually the same shape and size throughout their mouth.
6) Unlike mammals, reptiles can take care of themselves very soon after hatching. Some species of reptiles, like the American alligator will watch over newly hatched young for a time.
7) Some reptiles have a poisonous bite.
8) The study of reptiles is called herpetology.

Reptile Classification:
The class of reptilia is broken down into 4 orders (living today).
1) Crocodilia (crocodiles, caimans, alligators, gharials)
2) Testudines (turtles, terrapins, sliders, tortoises)
3) Squamata is broken down into  2 suborders:    

     a. Lacertila or Sauria (lizards)
     b. Serpentes (snakes)
4) Sphenodontia (tuataras)