MPN11.
Yes those stubs half way down the 'wings' were indeed the ablutions.
It was always a good idea to lift the seat with your foot and drop it a foot or so to get rid of any cockroaches that had a habit of lurking under the rim/seat. These were big buggahs, about 2 inches long, and could shift and even fly.
We never had any problem with mosquitos as after it rained, a little Maldivian guy would spray puddles with a paraffin mixture, and every week he would come round with a back pack machine that gave out clouds of blue/white smoke. If you were in trap one after a curry the night before, even despite your protestations, he'd stick it under the door so you got a face full!!!