Well, the search continues with help from Montezuma Historian Cheryl Longyear and Bill Hecht's site of old photos.You can find the collection that has these top photos here.
The top photo shows the bridge that carried the old West Shore (officially the New York, West Shore, and Buffalo Railway) over the Seneca just north of Montezuma. My guess is that the photo was taken from the old Rochester, Syracuse and Eastern Interurban Trolley line bridge. This bridge is no longer there.
The bottom photo is of the New York Central RR mainline bridge, a much more substantial structure as it carried four tracks across the river. This bridge is still being used.