The Ithaca side by side 12 gauge serial 188650 was made in 1927.
It is an Ithaca model NID made in 1926
You have an Ithaca sxs Flues model made in 1919.
1893 It was made in 1893 Made in 1893
According to a table in "Ithaca Gun Company from the Beginning" it was made in 1901.
If this is an old side by side it would be a Baker model made in 1886. Serial numbers of Ithaca shotguns for that year were 2448 - 4101.
I would say that you have a Ithaca model flues double barrel shotgun that was made in the year 1923,with the serial number that you provided.
The gun was made in 1902, and is a late 'Crass' Model. sales@countrygunsmith.net
Made in 1925
Look in "The Ithaca Gun Company - From the Beginning"
Ithaca 12 ga. double barrel side lock hammers serial # 43300
Known as the 'Minier Model' and made 1906-1908. sales@countrygunsmith.net