The tail is slender and heterocercal, the caudal fin deeply forked.
The caudal fin is at first symmetrical, but a special lower lobe grows out and gives to it a heterocercal character.
They have small scales, a heterocercal tail, and two dorsal fins with a strong spine in front.
The tail is asymmetrical (heterocercal), and numerous placoid scales (dermal denticles) are embedded in the skin.
The tail may be heterocercal, as in Acipenser, or diphycercal as in Polypterus.
The heterocercal tail is one in which the hindmost vertebræ are bent upwards.
The slender body is covered with small scales and ends in a heterocercal tail.
The tail is diphycercal, heterocercal, or else it degenerates into a whip-like organ, a form which has been called leptocercal.
In Dipterus there are no marginal teeth, and the tail is heterocercal, not diphycercal, as in the other Dipnoans generally.
The tail is heterocercal, but in some cases (Squatina) approaches the diphycercal condition.