The coin is 10-12mm bronze, and about 2mm thick, yet it appears to be a small flan for the die, or maybe trimmed/clipped, and the strike might be off center. Let's start with the reverse... It appears to have a figure standing or walking left, leaning or resting on a shield at the right. The text on the right appears to be "BAΣIΛEΩΣ" but only "ΣIΛEΩΣ" is visible. It seems that there is text on the left side but not much is available or visible on the small flan. I think I could be like "---OXO---"... maybe.?. Now, the reverse appears to have an (off center and worn) female bust, based on it having a ponytail or low bun. In my searches for the reverse lettering, I've scrolled through the coin images on Wildwinds for Seleucis, Antiochos, and Thessaly but found nothing really definitive so far. Anyone have any ideas or leads? Thanks in advance!
Some hints: Tall lanky pretty woman is often Apollo . If that figure is holding a bow, definitely Apollo. (If just a bust, look for hair that is partially up in the back, with lovely little locks left long along the neck... also Apollo, or if wearing an ivy wreath, Dionysos.) Legends written vertically are often Seleucid. (edited: oh, you already mentioned Seleucid. Keep looking in that direction. Wildwinds is not complete. Run you search in CNG's archives and in ACsearch. Check Vcoins too.)
Could that tall, vertically elongated D-shape be a bow instead of a shield? I didn't even consider that before...
DING DING DING! I THINK WE HAVE A WINNER! It certainly does look like this! WW Thanks so much you two! @Ajax & @TIF!