_Gen._ husa.
_Dat._ huse.

_Dat._ husum.
_Acc._ hus.

_Acc._ hus.
Hence our "collective" plurals, such as _fish_, _deer_, _sheep_, and _trout_.
There is also a weak declension, much the same for all three genders, of which the masculine form runs as follows:-- SING.

PLUR.
_Nom._ guma (_a man_).

_Nom._ guman.
_Gen._ guman.