Dictionary of Ichthyology
marsupium = the name applied to the brood-pouch in Syngnathidae and
Solenostomidae. In Syngnathidae it consists of a vascularized groove formed by
flaps of
skin along the underside of the tail of males
(subcaudal marsupium); in
Solenostomidae it is a
pouch formed by the pelvic fins, provided with many
long
filaments, and found only in the female (ventral fin marsupium).