Characteristic features of class - Reptilia are: 1. The class name refers to their creeping or crawling mode of locomotion (Latin, repere or reptum, to creep or crawl). 2. They are mostly terrestrial animals and their body is covered by dry and cornified skin, epidermal scales or scutes. Snakes and lizards shed their scales as skin cast. 3. They do not have external ear openings. Tympanum represents ear. Limbs, when present, are two pairs. 4. Heart is usually three - chambered, but four - chambered in crocodiles. 5. Reptiles are poikilotherms [cold - blooded animals]. 6. They lay eggs with tough coverings and do not need to lay their eggs in water, unlike amphibians. 7. Sexes are separate. 8. Fertilisation is internal. 9. They are oviparous and development is direct. 10. Examples: (Turtle), Tortoise, Chameleon (Tree lizard), Garden lizard, Crocodile, Alligator, Wall lizard, Poisonous snakes - Naja (Cobra), Bangarus (Krait), Vipera (Viper).