See this online ebook:
Catena Aurea: Commentary on the Four Gospels, Collected out of the Works of the Fathers by S. Thomas Aquinas: St. Mark (Oxford, London: James Parker & Co., 1874). [It appears from the Preface that the text was translated by John Dolbee Dalgairns and edited by St. John Henry Newman.] May be read online, and available in pdf, epub, mobi, and other formats, at Internet Archive and Open Library. An earlier edition (Oxford: John Henry Parker; London: J.G.F. and J. Rivington: 1842) is available at Internet Archive.
The text may be read online, together with the commentaries on the other gospels, through this page at e-Catholic 2000.
The Catholic Primer ebook, which omits the Prefaces of St. John Henry and St. Thomas (© The Catholic Primer, 2004), is available in pdf format on this page of Saints’ Books and at St Augustine Chapel.org.
For the Feast of Saint Mark. For other texts and ebooks, you may access the List of Free eBooks (Arranged by Title), the List of Free eBooks (Grouped by Subject), the List of Worth-It Catholic Books & eBooks, and the main page of the Catholic eBooks Project.
“Peter’s hearers… were not content with the unwritten teaching of the divine Gospel, but with all sorts of entreaties they besought Mark, a follower of Peter, and the one whose Gospel is extant, that he would leave them a written monument of the doctrine which had been orally communicated to them… And Peter makes mention of Mark in his first epistle which they say that he wrote in Rome itself, as is indicated by him, when he calls the city, by a figure, Babylon, as he does in the following words: The church that is at Babylon, elected together with you, salutes you; and so does Marcus my son. [1 Peter 5:13]” (Eusebius, Ecclesiastical History [312-324 AD], I, xv)