Head one trunk fused, neck not found, tail less, two pairs of limbs, hind legs with toes, vertebrae are ten, the last one is a urostyle, ribs reduced or absent, fertilization is external.
It is divided in to 5 sub orders.
Sub-order-I: – Amphicoela Amphicoelous, the inner dorsal and inner-ventral are certilagenous.
Examples: Liopelma, Ascphus (Bell Toad) etc.
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Sub-order-II: – Opisthocoela.
Vertebrae typically opisthocoelous. Free ribs in either larva or adult. Scapulae are shorter.
Examples:- Alytes, pipa etc.
Sub-order-III:- Anomocoela
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Sacral vertebrae procoelous, without free ossified ribs at any stage of development. PresacraL vertebrae eight.
Examples:- Peolobates, scaphiopus.
Sub-order-IV:- Procoela.
Vertebrae procoelous, presacral vertebrae 5, 8 in number without ribs, urostyle with double condyles.
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Example:- (i) Leptodacylus:- Maxillary teeth absent, a large parotid gland situated behind the eyes.
Buffo commonly known as toad. Terrestrial and nocturnal, hindes under logs or stones, skin rough situated behind the eyes.
Sub-order-V:- Diplasiocela:
Pectoral gridle, fused to sternum, centrum of the sacral vertebrae convex anteriorly and with a double condyle posteriorly. Eight vertebrae biconcave and first seven vertebrae procoelous. Ribs are absent.
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Example:- (i) Rana: Teeth in upper jaw, tongue, forked posteriorly.
(ii) Polypedates (Rhacophorus) (Tree-frog).
Microhyla (Narrow-mouthed toad).