Thanks for the information Janice! It was a help! I have been poking around the LDS site and found the Fergusson/Laurie tree you speak of. It leaves off with James Fergusson B: 6 Jul 1770 in Craigdarroch. Very interesting!
I have searched extensively but can't be certain that I am a decendent of this James Fergusson, nor have I been able to locate records of the birth of my great grandfather James. It is unreasonable to assume that James, born in 1770, was the same James who married my great grandmother Margaret Lyall in 1858, he would have been 88 years old and nearly 94 when my grandfather was born :) It is however compelling to speculate that James had a son James who is my great grandfather. It is possible too that our family derives from other decendents of Anna Laurie and Alexander Fergusson.
James Fergusson (1770) had a brother Robert Cutler FERGUSSON but he died in France in 1838 and I've found no record that he ever married.