Your specimen is very nice! It is well struck.
I have somewhat lesser specimen. I have always wondered why this type is attributed to Mytilene. It has no inscription. A few years ago I tried to understand how the attribution was done. Warwick Wroth's BMC catalog credits Percy Gardner, Barclay Head, and J. P. Six for attributing all electrum sixths to Mytilene although the works by those authors that Wroth cites just say Lesbos.
Because of a marble tablet inscribed with a treaty between the Mytileneans and the Phocaeans to regulate the standard of electrum coinage we know that Mytilene had electrum coinage. Mytilene is a good choice. I was never able to figure out why it was the only choice.
I cannot answer your question, but
Bodenstedt is the most recent
work on these.
*Very* basically, the coins with images on both sides are from Mytilene, and those
with the simple
incuse punch on the
reverse are Phokaian (these also have a Seal
somewhere on the
obverse: the Greek for Seal is ΦΩKH). Some of these Mytilenians
also occasionally have some
part of an
ethnic (eg: MYTI, ΛE, etc.).
There are a LOT of updates required to Bod., not least the dating. The date system
proposed is rather arbitrary and a
bit clumsy, and can be largely dismissed, except as
a broad and general guideline (groups, sequences {*with exceptions}, etc.). There
are other errors as well (
not a subject for this post).
The details of the Treaty appear valid, as it should, but apparently not for the entire
period in question, and the fixed two-year alternating spacing of issues has to be
questioned and then thoroughly updated. New dies and die-links are being found "all
the time" as it were, even a couple of new
types and many new varieties.
Bod. is in
German, and I have hoped for some time that someone would attack the
task of translating this into English, at least in
part (I can get my
head around some
of it, but not all). If anyone knows of such a translation, please let me know!
Walter
Holt 
