John Calvin Commentary Galatians 1:19

"But other of the apostles saw I none, save James the Lord`s brother." — Galatians 1:19 (ASV)

But I saw no other of the apostles. This is added to make it clear that he had only one purpose in his journey and attended to nothing else.

Except James. The identity of this James deserves inquiry. Almost all the ancient writers agree that he was one of the disciples, whose surname was “Oblias” and “The Just,” and that he presided over the church at Jerusalem. Yet others think that he was the son of Joseph by another wife, and still others (which is more probable) that he was Christ’s cousin on his mother’s side; but since he is mentioned here among the apostles, I do not hold that opinion. Nor is there any force in the defense offered by Jerome, that the word 'Apostle' is sometimes applied to others besides the twelve, for the subject under consideration is the highest rank of apostleship, and we will soon see that he was considered one of the chief pillars (Galatians 2:9). Therefore, it appears far more probable to me that the person of whom he is speaking is the son of Alpheus.

It is reasonable to believe that the rest of the apostles were scattered throughout various countries, for they did not remain idly in one place. Luke relates that Paul was brought by Barnabas to the apostles (Acts 9:27). This must be understood to refer not to the twelve, but to these two apostles, who alone were residing in Jerusalem at that time.