My last name is Lynes and I agree with that it is pronouced "lines".My people trace back to Kerry where they were born in the late 1800s with the last named "Lyne".Lyne (at least in Kerry) is generally presumed to be the anglicized version of the Gaelic "O'Laighin" meaning gray.See "The Surnames of Ireland" by Edward MacLysaght (1957).
MaLysaght also talked about the many variants, depending on where you lived...these include Lane, Lehane, Leyn, and Lyons.Lyon is a Scots name and there is some thought that Lyons traces back to Norman French.
I think thatthere is a lot of room drift in spelling and pronuciation over time. For example, I have a copy of the spring 1901 census of Ireland and the family name is Lyne.By the fall of the same year, my grand uncle Pat -- the first of the family to come to the US -- is signed in at Ellis Island as "Lynes.". How he added an "s" to his name is a mystery!(My Grandfather Dennis, Pat's younger brother, went even a step further, being born "Denis Lyne", passing thru Ellis Island in 1910 as "Denis Lynes" and dying in 1961 as "Dennis Lynes"...adding letters to boyh his first and last names over his lifetime.)
OK...more than you wanted to know!But it is pronounced "line" or "lines"!