The class Reptilia is divided into the following ten orders, of which the first four are represented by living forms, whilst the remaining six are extinct:

1. Chelonia (Tortoises and Turtles).

2. Ophidia (Snakes).

3. Lacertilia (Lizards).

4. Crocodilia (Crocodiles and Alligators).

Recent.

5. Ichihyopterygia.

6. Sauropterygia.

7. Anomodontia.

8. Pterosauria.

9. Deinosauria. 10. Theriodontia.

Extinct.