Important examples of rude sculpturings appear upon the walls of certain natural, or perhaps semi-artificial, caverns occurring at Knockmore, close to the village of Derrygonnelly, Co. Fermanagh. The chief of these is the ‘Lettered Cave,’ so called from the carvings of an early date with which its sides are scored. The dimensions of this singular retreat are as follows:--Height, at the mouth, 10 feet 5 inches; these proportions gradually lessen to a distance of about 18 feet from the external opening. There the passage takes an oblique turning to the southward, and continues to a distance of about 9 feet further into the heart of the limestone. The height of the chamber at its extreme end is about 5 feet. The opening faces north-east, and is well sheltered from the wind by a grassy knoll, which extends, right and left, in front. There is every reason to believe it was long used as a habitation or place of retreat. The markings are placed, without any attempt at symmetrical arrangement, upon almost every smooth portion of the rocky surface of the interior. Many are extremely well marked; others have become all but obliterated through the influence of time, the efflorescence of the stone, and the action of persons who have in many places scraped away the ancient figurings, or portions of them, in order to find space for inscribing their respective names; but, nevertheless, a considerable portion of the old markings remain in excellent condition. These scribings consist for the greater part of a number of figures and designs usually considered, by archæologists, as prehistoric. But whatever may be the age and character of such carvings, there can be no doubt amongst antiquaries that an elaborately-formed interlacing cross, which may be seen engraved upon the left-hand side of the entrance to the cave, must be referred to an early Christian period. Knockmore contains on its northern side, in a situation rather difficult of access, a second scored and partially artificial cavern. This little eyry, which is only large enough to retain in a recumbent position two, or at most three, persons of ordinary size, must, while yet the slopes of the knock were covered with trees and brushwood, have formed a very secure retreat. That it was inhabited in early days is certain, as upon digging up a considerable portion of the floor, indications of fires having been used were traceable on at least three separate levels. At a little distance from the surface, amongst burnt-looking earth and particles of wood charcoal, Mr. Wakeman found some bones of animals which had been used as food. They were generally very small, and difficult of identification, but amongst them occurred those of the red deer. The carvings here are rather of an elaborate character, and form an interesting combination of the older style of sepulchral rock-sculpture with what is generally considered early Irish work, but of a period subsequent to the spread of Christianity in this country.[17]