The blade of the caudal fin is then divided into two nearly equal portions, and is said to be diphycercal.
He named it falcata, or "scythe-shaped," from the curving of the caudal fin.
It may be objected that the longitudinal muscles were too small to permit the use of a caudal fin.
Head, about one-fourth of the whole length from the snout to the base of the caudal fin, varying much with age and size.
The caudal fin has never true spines, though at the base of its lobes are often rudimentary rays which resemble spines.
The caudal fin is at first symmetrical, but a special lower lobe grows out and gives to it a heterocercal character.
There are two dorsal fins, slightly connected; the caudal fin is double concave or trifurcate.
The caudal fin, however, undergoes a more complicated metamorphosis.
The dorsal fins are but slightly separated, and the caudal fin is almost square.
The haemal spines of the turned-up tip of the tail are flattened (hypural bones) and serve to support the caudal fin rays.