Hogwarts - Prefect

[Jim Ferer]

No: HPFGUIDX 22079

Melanie:"Yes but does there have to be a male and a female [prefect 
in each house]?  And are there just 2, to my knowledge it isn't stated 
that there are only 2 prefects for each house.  I don't know though, 
it's just a thought."

Practically there has to be. Who's going to keep order in the girls' 
bathroom, or figure out who put a Shrinking Charm on Lavender Brown's 
brassiere?