Looks good to me.
It is a late imitation (100-50 BC) of the greek Massalia Drachms, made by celtic
tribes in the Gallia
Cisalpina (today northern Italy
). The style
and the low weight of the coin points to the late examples of that type
, 2.21g for your coin is ok and within the range. Style
is also ok, so far as I can see from the pics there is no doubt about the genuiness of the example.
Cataloge references: Castellin 1009-1035, Dembski
Look here for an (early) example:http://www.forumancientcoins.com/board/index.php?topic=85564.msg533653#msg533653