Class : Amniota - Reptilia - sub phylum - Tetrapoda

Class : Amniota - Reptilia - sub  phylum - Tetrapoda

Tetrapoda

The vertebrates with two pairs of limbs adapted for locomotion on land are known as tetrapods. The limbs are of pentadactyl type. The tetra-pods are identified by a cornified outer layer of skin and nasal passages communicating with mouth cavity and lungs. The super class Tetrapoda is divided into four classes namely. Amphibia, Reptilia, Aves and Mammalia.

Amniota

The tetrapods like reptiles, birds and mammals are referred to as amniotes. The amniotes have certain membranes associated with embryos inside the egg. It is an adaptation in terrestrial forms during development. These membranes are the amnion, chorion and allantois.

Class : Reptilia

Reptiles are represented by lizards, snakes, turtles, tortoises, alliga-tors, crocodiles and the tuatara lizard, Sphenodon punctatum.

The body is variable in shape. It is covered with an exoskeleton of horny imbricate epidermal scales. Skin glands are practically absent. The limbs are of pentadactyl type adapted for climbing, running and paddling. The en-doskeleton is well ossified. Respiration is by lungs. The heart is three cham-bered (In crocodiles it is four chambered). The functional kidney of the adult are metanephros. The Sexes are separate. Fertilization is internal. The eggs are covered with leathery shells. Reptiles have developed some form of copu-latory organ to transfer the sperms into the cloaca of the female.

Example : Garden lizard, Cobra, Monitor lizard, Crocodile, Turtle.