In the Gospel of St. John, Bartholomew is not mentioned among the Apostles, but it is stated that Philip and Nathanael came to Jesus, and that Jesus said of Nathanael, “the Israelite in whom was no guile.” In the list of the apostles in the other Gospels, Nathanael is not mentioned, but after Philip is placed Bartholomew.
The Redeemer chose all the apostles at once, and formed them from the beginning into a hierarchial group with St. Peter at their head, in order to show us that the rightful priesthood instituted by Christ is that which is derived in unbroken succession from the twelve apostles chosen by Our Savior, and being in communion with the See of Peter, is also in communion with the entire Catholic episcopate.
Bartholomew is said to have preached the faith over a great part of Asia and suffered martyrdom in Armenia, where he was flayed alive. His body was transferred many times, and is now believed to repose in the Church of St. Bartholomew on an island in the Tiber.
(Source: The New Roman Missal, Rev. F. X. Lasance)