We then come to the apsidal chapel which flanks the southern side of the sacristy. The chapel is dedicated to saint Samson and dates to the first half of the 14th-century, being built during the episcopacy of Jean du Bosc (1312–24). A number of bishops were buried here including du Bosc. The north and south walls have stone benches. There are three large bay windows with stained glass dating to 1859 . These three windows by René Échappé depict various Dol bishops and under each of these depictions is a small medallion showing an event in that bishop's life. They were all executed in 1859 and take up three of the cathedral's many bays. The first of these windows features four lancets containing depictions of saint Budoc, saint Magloire, saint Samson and saint Génevé. The scene shown under saint Budoc who was the 3rd bishop of Dol depicts Monseigneur Brossais-Saint-Marc being presented by saint Melaine, the 1st bishop of Dol to saint Samson and offering him a window. Beneath saint Magloire who was the 2nd bishop of Dol, the scene shows the Comte de Jersey giving the bishop part of his land. Samson was the 1st Dol bishop and beneath his image, the scene shows Samson studying a plan of the monastery he will have built in the future. Finally under saint Génevé are the arms and motto of Monseigneur Brossais-Saint-Marc.