I can't remember it containing anything but reptiles, although the 1959 map, shown elsewhere in this gallery, describes it as 'Rhesus Monkey Cottage'. It had a bit of a face lift not so long ago but there's not a lot to see - most of the tanks are well away from the viewing window.
In my guidebook from 1983 it is labelled for Barbary apes. I think that there was an outdoor area to the left of the building (as seen above). There was a path to the right which led down to the Sub-tropical House and aviaries near the main road; they are now all demolished and that area is part of the current car park.
@gentle lemur I didn't realise what building I was looking at here. Yes, it had the Barbary Apes for a while- there were glass-fronted(?) indoor cages too. I think it has also done service as an 'education or T.V.' centre at some stage too.