Finally! After tracking down Johannes Kunze's 1895 German book that includes the Greek text of Marcus Eremita's treatise "Against the Nestorians," I found, at the end of chapter 6, the following:
". . . KAI OUTWS DE OUDEN BLAYOUSI TOUS BEBAIOPISTOUS. KAN QANASIMON TI PIWSIN, OUDEN AUTOUS BLAYEI."
(This is on page 10 of the Greek text in Kunze's book (available at Google Books), lines 18-19.)
A clear use of Mark 16:18. Kunze identified Marcus Eremita as a monastery-leader in Ancyra, in the early 400's, who decided to leave the monastery and become a hermit (thus the title "Eremita") -- according to the article at New Advent (taken from another source), Marcus Eremita was a hermit "probably in the desert east of Palestine, near St. Sabas." The same article says that Marcus Eremita was a contemporary of Nestorius and probably died before the Council of Chalcedon. It also states:
"The discovery and identification of a work by him against Nestorius by P. Kerameus in his Analekta ierosol. stachyologias (St. Petersburg, 1891), I, pp. 89-113, makes his period certain, as defended by Kunze."
Yours in Christ,
James Snapp, Jr.