This work was compiled to supplement the magnum opus of Irish genealogy, John O'Hart's book "Irish Pedigrees" and can be looked upon as the missing third volume. It consists, in part, of 257 additional genealogies of Anglo-Irish and Anglo-Norman families that settled in Ireland following the English invasion. Notwithstanding the importance of the pedigrees, which fill out the first 225 and the final 75 pages of the text, the Appendix to the volume may take on ever greater importance. Comprising half of the volume, the Appendix consists largely of abstracts of primary sources that were destroyed in the Public Record Office fire of 1922. Among the most important records "preserved" by O'Hart are lists of Forfeiting Proprietors in Ireland, arranged by county and thereunder by barony; Persons Transplanted in Ireland, arranged by county; Irishmen who served in the Spanish Netherlands during the exile of Charles II; a number of lists relating to the seventeenth-century land settlements in Ireland, including Names of Persons in the [Land] Grants, persons restored to their former estates, Grantees and Purchasers of Estates forfeited in Ireland under the Williamite Confiscations; and lists of the Irish Brigades serving in France and America in the 18th and 19th centuries. In all, this prodigious work contains more than 22,000 references to surnames found in the volume, each of which is easily found in the index at the back.