[R] how to combine 2 3d scatterplots

[mb622 at york.ac.uk]

hi,

I am new to R and i have managed to create 2 3d scatterplots with R and 
Iwaswondering if there is a way to connect them.

I was also wondering how i can add arrows to the plot similar to the 2d 
comment arrows()?

Mandy