Mounting partitions

[alan duval]

I have installed a larger 500G HD, and used Gparted to make 4
partitions.
Partition 1 for Ubuntu9.04
Partition2 for Swap
Partition3 for Home
Partition4 for Virtual operating systems
        
I then transferred Ubuntu and my Home partition from my smaller disk to
the larger using Acronis.
However Ubuntu then couldn't mount the new Virtual partition. Message
said
"Can't find sda7 (my virtual partition) in /etc/fstab or /etc/mtab". 
I looked at fstab but didn't know what values to put for sda7.
I then opened mtab and it looked simpler, so I added the line:
/dev/sda7 /Virtual ext3 rw,relatime 0 0
which is similar to the line for sda6

This then loaded my Virtual partition in the media folder and I am able
to use it but I notice that the line I inserted in mtab has disappeared.

Although this works I doubt that I have followed accepted practice.

Could someone enlighten me as to the correct procedure for mounting a
partition which is not shown in fstab or mtab?

Alan