The Celtic monks of the early centuries showed a strong predilection for islands as the sites of their monasteries. Almost every loch and river show evidence of this choice in the ruins scattered over the country, and some small detached and rocky islands situated a few miles from the West Coast of Ireland (where they have been little exposed to disturbance) yet contain specimens of the above primitive structures. The great enclosing cashels and the singular beehive huts have been beautifully illustrated and described in the splendid work of the late Lord Dunraven on Ancient Irish Architecture, edited by Miss Stokes. It was one of the peculiarities of the Irish monastic system to encourage the members to retire occasionally for a lengthened period to some solitary place, where they might do penance and worship undisturbed. These places of retreat were called “deserts,” and were sought for in the uninhabited and rocky islands lying at a distance from the mainland. It is surmised that the islands of St. Michael, Ardoilean, and others in a similar position off the West Coast of Ireland, containing monastic remains, were retreats of this description. We have seen that these establishments exhibit in their beehive huts and cashels the tradition of the native Pagan style of building derived from the raths of the converted chiefs. In addition to these primitive erections, they further contain evidences of certain structural elements imported in connection with the introduction of Christianity.[15] For, besides the circular cells of the monks, they invariably comprise one or more small churches or oratories. These are structurally distinguished by having square angles on plan, both externally and internally, and by having the joints of the stones generally cemented with a certain amount of mortar. The roofs were constructed like those of the huts, with overlapping stones carried up with a curve to a pointed ridge. These churches are of small dimensions, and form a simple oblong chamber set with its greater length towards the east and west. They have a small door in the west end with inclined jambs and straight lintel, and a small square-headed window to the east. The above Christian form of church was, however, not fully adopted at first, many of the early Irish churches retaining the native form of construction--_i.e._, the walls, both of sides and ends, rise in a curve from the foundation to the ridge of the roof, which is formed of overlapping stones, and the whole presents the appearance of an inverted boat with a sharp keel. These churches are built with dry stones, carefully constructed.[16] They are often associated with pillar stones, inscribed with crosses and inscriptions in Roman letters of the most ancient form,[17] and are supposed to be of the age of the Saints whose names they bear, dating from the fifth to the seventh centuries.[18] They were succeeded in the seventh and eighth centuries by a somewhat more advanced type, forming a