I think we can read (visible letters in bold):
D N ... ... CONS
TANTIVS AVG
The "A" looks like an "H", as often. So, I think, Constantius II. I suspect it's a portrait from soon after he took the title of Augustus (= emperor) in 337. If I'm not mistaken his head is normally "longer" in later issues.
Search secvritas
on the Wildwinds page. The legend on the reverse being
SECVRITAS REI P(ublicae)
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