James was working as a farm servant so he may have moved about to take advantage of available work. Most did and it makes them hard to trace. His townland/address at the time of his marriage appears to be Bohasset but that may not be where he came from. I searched the tithe applotment records for any Eugene McCarrons in that area. (Farmers didn’t move about much, and were normally listed in the tithes). The nearest I can see were Owen McCarron in Sessiagh, in the parish of Cleenish in 1834:
http://www.irishgenealogyhub.com/fermanagh/tithe-applotment-books/parish-of-cleenish.php
There was another in Millwood, Aghalurcher in 1833:
http://www.irishgenealogyhub.com/fermanagh/tithe-applotment-books/parish-of-aghalurcher.php
(Owen & Eugene are interchangeable as I expect you know).
You might want to check the records for those 2 parishes to see if you can find a match for James baptism.
This looks to be your family in 1901:
http://www.census.nationalarchives.ie/pages/1901/Fermanagh/Dresternian/C...