Who's missing from this picture?

This is the COUPER family of Oakleigh, Victoria, Australia. Someone is missing, but who?


In the middle is Mary COUPER (nee ALLSOP), wife of Daniel Miller COUPER. Obviously he's not in the photo, that's not the answer I'm looking for!

Mary and Daniel had nine children, all of whom survived infancy. However, there are only eight children in the photo.

The children were:

1. Jessie Isabella COUPER (F) b.1880
2. Robert John COUPER (M) b.1882
3. Lucy Ellen COUPER (F) b.1883
4. Alfred Edward COUPER (M) b.1885
5. Ethel Mary COUPER (F) b.1886
6. Leslie Miller COUPER (M) b.1887
7. Charles Henry COUPER (M) b.1890
8. Ruby Maude COUPER (F) b.c1892
9. Albert Donald COUPER (M) b.1894

The more I look at it, the more convinced I feel that the picture was taken c1893, before the birth of Albert Donald COUPER. That would give an age range for the children pictured of about 1 or 2 to about 13. Four girls and four boys with the youngest, Ruby, on her mother's lap.

That may seem the obvious conclusion, but another possibility is that the photo was taken after the death of Leslie Miller COUPER, who was accidentally killed by a horse at age 9 in 1897. This would make the age range of the children about 3 to about 17. Still four girls, four boys but now it's little Albert in Mary's lap. I'd also have to reverse my assumption about the gender of one of the other children.

So, is the youngest child a girl aged one or two, or a boy of age three or more? I think the former. What do you think? Any other clues or observations?