Hi
let me guess on this, this is the MISTERY LEGION
The XVII was one of the 3 legions lost at Teutoburger Forest in the Varrus disaster, where it lost its Aquila and was never rebuilded.
I think it was stationed on 15 BC in Xanten (Castra Vetera).
It was probably raised by Augustus and might have then an Capricorn as emblem but can be a Lion or something else
Some good speculation can be read here, it might be true or not:
http://www.livius.org/le-lh/legio/xvii.html
Finally you choose a hard one but you can be creative and I think an Capricorn looks better then an Lion
an interesting book would be:
•R. Wiegels, "Legiones XVII, XVIII, XIX", in: Yann Le Bohec, Les l�gions de Rome sous le Haut-Empire (2000 Lyon) 75-8
http://books.google.co.uk/books/about/Le...edir_esc=y