homocercal

from WordNet (r) 3.0 (2006)

homocercal
    adj 1: possessing a symmetrical tail that extends beyond the end
           of the vertebral column (as in most bony fishes) [ant:
           {heterocercal}]

from The Collaborative International Dictionary of English v.0.48

Homocercal \Ho`mo*cer"cal\, a. [Homo- + Gr. ? tail.] (Zool.)
   Having the tail nearly or quite symmetrical, the vertebral
   column terminating near its base; -- opposed to heterocercal.
   [1913 Webster]