In the Housebook, Children of Luna page, the monkey is sitting on the shoulder of the hornplayer standing next to the Bateleur.
Keeping in mind that this is simply another identifying element of the Bateleur, and doesn't need to carry some massive conspiracy of hidden meaning, I don't see why there shouldn't be a monkey there.
Although it's odd...
I see the monkey's face just above where rosanne has brought it out...
So maybe it's just an inkblot...
Or maybe it's a second figure standing behind him, wearing a hat that looks like a turban, with a star in the middle of it....
And I don't see why there would be an indistinct fish, in some oddly upright position, on the Star card. Especially when that odd graphic convention for an "embankment" is established in so many other places, and seems also to appear on the Moon.
Plus-which-wise, I don't think one should try to date this thing by the style of the costumes. Why should one assume that they would have been current when it was made? All you can do is set the earliest date horizon by that.
And another thing, I think rosanne has the right idea with the concept of pattern sheets being important, but I don't think this is one, because of the two wands cards. (Curious to know if they're pasted on.) It is believed that The Housebook was made in part or in full by The Master of the Amsterdam Cabinet, who probably copied visual passages from The Master E.S.'s deck of cards, who probably used a pattern book to design them in the first place, and so on. Images were recycled, and sometimes specific details that seem significant may be included simply because they were copied along with everything else in the source model. (At the same time, it would be most interesting of all to find the original model, and see what specifics were ADDED or altered....)
Hmpf.
Back under my rock...
