Early Christian graves were usually marked by stones nowise differing from the pagan pillar-stone, except that in some instances they were sculptured with a cross. These were of the simplest form and rudely cut, and consisted of an elementary line cross, or one slightly developed and within a circle. Plain undressed slabs or rude stones were generally adopted in the first instance, the only use of the cutter’s instrument being on the incised work. Many of the stones of this class are found in old Christian graveyards, or within the area of early monastic establishments. The richest collection of them is to be seen at Clonmacnoise, numbering 188; and inscribed slabs to the number of 74 have been lost from this one spot alone. Clonmacnoise was founded by St. Kieran in the middle of the sixth century; and, in time, it was, as Ware says, ‘above all others famous for the sepulchres of nobility and bishops.’ Petrie, in his work on _Christian Inscriptions_, shows, by means of the recorded names and ‘Annals,’ that for over 600 years, beginning with 628 A.D., this class of monument was used for sepulchral purposes. The inscribed crosses are of great variety--Celtic, Latin, and Greek--many being very chaste with key-end and other patterns. The most typical form of Celtic cross is that formed from the plain Latin type enclosed in a ring that connects the arms, and leaves varied spaces between it and the corners of their intersection. [Illustration: Early Crosses on sepulchral slabs at Clonmacnoise.] This style of memorial appears to have been succeeded by a rudely-formed cross, the arms of which are little more than indicated, and which is usually fixed in a socket, cut in a large flat stone. Such crosses rarely exhibit any kind of ornament; but occasionally, even in very rude examples, the upper part of the shaft is hewn into the Celtic form already described, the portions of the stone by which the circle is indicated being frequently perforated or slightly recessed. A fine plain cross of this style may be seen on the road adjoining the graveyard of Tully, Co. Dublin; and there is an early-decorated example near the church of Finglas, in the same county. [Illustration: Cross on slab, Clonmacnoise.] [Illustration: Cross on slab, Clonmacnoise.] [Illustration: Cross on slab, Clonmacnoise.]