[ubuntu] Accessing /dev/sdb2p*

I upgraded a dual-boot machine, which involved repartitioning the disk. Before I did so, I ran dd from the installation CD (16.04LTS) and imaged /dev/sda to an exteal drive on /dev/sdb2 (the system had already created /dev/sdb1, i think for swap). fdisk tells me that that drive contains /dev/sdb1 and /dev/sdb2, which in tu contains /dev/sdb2p1 thru /dev/sdb2p7, all with the expected size and attributes. So far, so good.
I want to mount /dev/sdb2p6 (the original /) so I can retrieve some stuff from the old ~.

Attempting to mount /dev/sdb2p6:
peter@Orion:~$ sudo mount /dev/sdb2p6 here
mount: special device /dev/sdb2p6 does not exist

Attempting to mount /dev/sdb2:
peter@Orion:~$ sudo mount /dev/sdb2 there
mount: wrong fs type, bad option, bad superblock on /dev/sdb2,
missing codepage or helper program, or other error

So, how can I mount /dev/sdb2p6, or otherwise access its contents?

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