adjective. Relating to, designating, or characterized by a tail fin having two symmetrical lobes extending from the end of the vertebral column, as in most bony fishes.

In ichthyology, having the caudal fin symmetrical as to its upper and under halves: opposed to heterocercal. See heterocercal, diphycercal, hypural.

adjective. Having the tail nearly or quite symmetrical, the vertebral column terminating near its base; -- opposed to heterocercal.

adjective. Describing the symmetric tail of a fish that has two lobes extending from the end of the vertebral column.

adjective. possessing a symmetrical tail that extends beyond the end of the vertebral column (as in most bony fishes)

"These are the even-lobed, or homocercal (Fig. 68), and the uneven-lobed, or heterocercal (Fig. 69)."

diphycercal  heterocercal  protocercal