The structure begun to be erected in continuation of the south transept has already been referred to. The building (see Fig. 571) is 57 feet in length by 25 feet in width internally, and comprises four bays in the length and two in the width, supported on three central pillars. The entrance is from the wide landing of the staircase in the south transept leading down to the lower church, from which point a series of wide steps leads down to the floor. From these steps a good view is obtained of the interior (Fig. 605). [Illustration: FIG. 604.--St. Mungo’s Cathedral. Details of Rood Screen.] The pillars are all moulded and provided with caps and bases, and the arches springing from them have numerous moulded groins with large foliaged bosses at the intersections. A substantial stone bench surrounds the outer walls; on this rest the bases of the responds and the sloping sills of the windows. Externally the building is plain (see Fig. 593), and has evidently been prepared for an upper story. It has a heavy moulded base, which is returned round the buttresses. The section of this base (see Fig. 573) is different from those of the nave and choir, and is doubtless later, the base of the main building being (as above mentioned) carried through this wing, which abuts against it. The buttresses of the main building are also carried down to the base, and the walls and arches of the crypt abut upon them. The doorway is evidently much older than the crypt. The windows have plain tracery, and over each window is a small panel containing a piece of sculpture, probably representing subjects from a mediæval bestiary, such as those referred to in Vol. I. p. 19. They look older than the building in which they are inserted. [Illustration: FIG. 605.--St. Mungo’s Cathedral. Interior of Blackadder’s Crypt.] It is conjectured from the following inscription on the vaulting, “This is ye ile of Car Fergus,” that this structure was begun at an early period, and that it was completed by Archbishop Blackadder, whose arms, surmounted by his mitre, are carved on the central buttress at the south end, and also on the corbel of a niche at the north-west angle. It is difficult to decide either the date or the purpose of this structure. It [Illustration: FIG. 606.--St. Mungo’s Cathedral. Monument to the Barons of the House of Mynto.] has evidently been intended to be carried higher, and probably may have been meant to form an extension of the transept. Although the work in the interior has considerable resemblance to that in the lower church, it is decidedly later, and has been copied from it. The work on the exterior is very much inferior, and the carving of the caps, which seems also to be imitated from that of the choir, is evidently late and debased. The groin ribs, too, are coarse, and point to about the time of Bishop Blackadder. [Illustration: FIG. 607.--St. Mungo’s Cathedral. Part of Monument, enlarged.]