from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. 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.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Describing the symmetric tail of a fish that has two lobes extending from the end of the vertebral column.
from the GNU version of the Collaborative International Dictionary of English
- adj. Having the tail nearly or quite symmetrical, the vertebral column terminating near its base; -- opposed to heterocercal.
from The Century Dictionary and Cyclopedia
- In ichthyology, having the caudal fin symmetrical as to its upper and under halves: opposed to heterocercal. See heterocercal, diphycercal, hypural.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adj. 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).
Now, in the development of a teleost fish (Fig. 68), as has been shown by Alexander Agassiz, the tail-fin is first like Fig. 70; then becomes heterocercal, like Fig. 69; and, finally, becomes homocercal like Fig. 68.
The lecturer dwelt chiefly on the argument of Agassiz, which he summarises as follows: "Homocercal fishes have in their embryonic state heterocercal tails; therefore heterocercality is, so far, a mark of an embryonic state as compared with homocercality, and the earlier heterocercal fish are embryonic as compared with the later homocercal."