Supposed Roman-British Coin

[Givety01 0]

Greetings Coin Enthusiasts,

I had recently purchased a set of uncleaned Roman Coins, some of which that were labeled "Roman British Coins."

After some light cleaning, I was able to reveal some recognizable characters and the face of what I believe is a Roman leader (too soon to tell if its an Emperor). That said, I would be delighted if someone can help me in identifying who is on this coin, etc.

My Art-History degree and knowledge I have of other Roman British coins would lead me to believe this is a very crude and possibly early minting. The lack of facial detail and spacing of the few letters (in comparison to other Roman coins from late BC to early AD) just seem too"archaic" for it to be a coin from the early AD, but that is why I am asking you friendly lot.

The letters on the back of the coin are more bold but in a less-recognizable "graphic" font, and what looks like a "6" turned 90 degrees to the left. It also appears that there is a man on horseback, or something of the sort.

I'm thinking this is also a copper-alloy coin, and I should note it's surprisingly thin. I believe it is a "semi" in size.

Very eager to find out who and what this is.
 

[Givety01 0]

Here is the back of the coin:

 

[Colin G. 147]

Looks like a 17th Century Lithuanian Solidus

[azda 973]

I think this is what i'm seeing

 

http://www.ebay.com/itm/R-LITHUANIA-POLAND-LOT-SCHILLING-SOLIDUS-1660s-JOHANN-CASIMIR-FINE-DETAILS-/282231807075?hash=item41b6539c63