Valens, AE3, Arles, 367-375 AD.

DN VALEN-S PF AVG, pearl diademed, draped, cuirassed bust right.
GLORIA RO-MANORVM, emperor advancing right, holding labarum 
and dragging kneeling captive behind him.
Mintmark: TCONST.

RIC IX Arles 16b, type xiv (c) var (unlisted mintmark).

RIC does not list any mintmarks with the ST ending for
this reverse type. In addition, the TCON mintmark types
usually have the captive upright, not kneeling. 

Sold on ebay August 2010 by "farmbig", Canada.