G /. Rofe — On Lithodomoiis Perforations. 



rangement, //representing tlie strata of hard rock, and g g the softer 

 beds, which are from 100 to 150 feet from ridge to ridge. The dip 

 of the strata is greatly exaggerated, as it does not exceed 9°. 



It is under the above-named ledges that the borings in question 

 occur, and generally near the edge, as will be seen in Fig. 1, PI. I ; 

 but the hole marked & is seven and a half inches from the outside. 

 The holes are bored upwards into the rock, and all have circular 

 openings of nearly the same size, a little more or less than seven- 

 eighths of an inch in diameter ; but the chambers within the rock vary 

 very much in size and shape ; some are nearly but not quite straight, 

 and about the same area of section as at the opening, whilst many 

 branch into several chambers, as shown on a larger scale in Fig. 2, 

 which is a horizontal section of the chambers, of which the opening 

 is seen at a in Fig. 1, the oval aperture being the opening in 

 perspective. Fig. 3 is a vertical section of the chambers connected 

 with the hole near the middle of the fracture shown in Fig. 1, the 

 section of the opening being at the upper part, and the chambers, 

 it will be seen, are of greater diameter than the opening. I have 

 forwarded the specimen figured in Plate I. to the British Museum. 



The burrows described by the above-named authors, in those cases 

 in which the direction of the borings is named, are stated to be bored 

 upwards from the underside, or, where on the face of the rock, ta 

 an upward direction. 



The Eev. T. G. Bonney, in his paper in the November (1869) number 

 of this Magazine, describes the holes as being bored generally upwards, 

 but of those described in page 486, No. 5 descends slightly, and 

 No. 6 is at right angles. The borings, however, shown in Fig. 1 

 in the plate illustrating his paper have very much the appearance 

 of being vertical sections of burrows, the front halves of which have 

 been removed with the face of the rock by weathering or fracture, 

 leaving the other halves as the curved chambers shown in that plate, 

 and very similar to some fractured chambers at the lower edge of 

 Fig. 1, PL I, of this paper : in that case (5) might be a chamber 

 from another boring, and (6) would clearly be a chamber from (8). 

 I am the more inclined to think this to be the case, as Mr. Bonney 

 describes some of the channels to be much weathered. 



We may now consider the origin, of these holes : first, then, as to 

 atmospheric action or weathering. The appearance as well as the 

 situation of the holes is altogether opposed to this theory, as they 

 are mostly on the under-surface of the rock, where no rain could 

 possibly get to them, either directly, by splashing, or by percolation ; 

 and they are generally in sound hard beds, and in those cases where 

 they are on the face of the rock, they are stated to be in sheltered 

 situations and bored upwards. Surely we have no right to assume 

 such partial atmospheric action as would account for holes so deep 

 in proportion to their diameter, and particularly as, from their posi- 

 tion, moisture could not lodge in them. It has been suggested that 

 possibly they might be caused by a decomposition of the rock, by 

 which fossils liave been loosened and have fallen out, leaving the 

 cavities ; but this is met by the fact that most, if not all, the holes 



