Galley
type with mark in left
field is
RIC 248.
RIC authors made mistake with position of mark (they list it as right same as
Phoenix) and
rarity rating of course, but
http://www.tesorillo.com/aes/027/027i.htm lists them correctly.
Both
Phoenix and Galley are really
scarce, I have 1st, 3rd and 5th
officinae of
Phoenix type RIC 247, and have seen around dozen pieces in total.
But Galley
type, or
RIC 248 is much harder to come by, I only saw three examples so far. And I have been maniacally checking every
ebay listing for years, looking for those
rare Siscian coins.
And regarding alpha or delta on Siscian
mintmarks, first rule could be if they touch on top its delta, if they resemble H or N or I I its alpha, but again I have coins which defy this rule.