Hello Ann -
I have irish relatives in Australia, but thru my O'Sullivan line. Most of my Irish came to the States and primarily to the Boston area.
Anyways - I have spent some time with these Keohane (and the variable spellings including Cuhane) over the weekend and it appears this Keohane family is from The Island. Not only did I find some of the younger siblings in the 1901 census, but I found baptismal records on irishgenealogy.com that say "Island". I am almost certain this is the Keohane family I found in Cambridge MA.
I should note, I am only related to this Keohane family thru marriage. I will list the family below - but Patrick Keohane married Mary Ellen Hurley from Ballymacshoneen in Cambridge MA - she being a sister to my great grandfather Daniel Hurley. The reason I was tracing out this family is because when these Hurley's, Keohane's and Donovan's (I will explain) arrived in the US, they all used the same addresses: 13 Fourth St, 20 Bristol St, or 6 Bristol St in Cambridge. I assumed they were all related, or at the very least knew each other in Cork.
A Timothy Donovan who married a Mary Hurley owned 13 Fourth St. A Jeremiah Donovan (a brother to Timothy Donovan I believe) who married a Nora Hurley owned 20 Bristol. A Keohane family also lived at 20 Bristol. A Keohane family also owned 6 Bristol.
The Keohane family from Island was:
Michael Keohane b. ~1831
Nora Donovan b. 1849
Looks like they married in July 1863
Known/probable children were:
Margaret 1864
John 1867 (migrated to Cambridge)
Nelly b. 1868
Laurence b. 1872 (in Ireland 1901)
Michael b. 1874 (migrated to Cambridge)
Kate b. 1877 (in Ireland 1901)
Patrick b. 1878 (migrated to Cambridge)
James b.1885 (in Ireland 1901, migrated to Cambridge)
Phillip b. 1889 (in Ireland 1901)
These are the children I know of.
These families are all from West Cork. I am not certain how they are related other than possibly thru the Donovan's - who I know the least about. The Hurley's are from Ballymacshoneen. The Keohane's are from The Island. I have the various Donovan families traced in Boston....but not sure where they came from, other than Cork.