39^0 Professor T. G. Bonney — Eroded Rocks in Corsica. 



others again sink deep into the stone, certain of tbera running 

 either upwards or sideways ; occasionally they reminded one, 

 though of course they were much larger, of the borings made 

 in limestone by snails.' One resembled those photographed by 

 Mr. Tuckett (except that the eroded hollow was higher up the side 

 of the block), and I think a big lad might have curled himself up 

 inside. The surface of the blocks was in fair preservation, for 

 though the felspar was rather dulled and whitened it was not at 

 all rotten;- that of the hollows was smoothed, occasionally almost 

 glazed, but the porphyritic felspar-crystals were often just prominent 

 enough to catch the eye and be felt by the finger. The majority of 

 the hollows looked towards the west; the remainder faced to the 

 other points of the compass, sometimes more than one way on the 

 same block, and they were at various heights from the ground. 

 The group represented in PI. XIII, though not one of those which 

 I saw, gives an excellent idea of some of the hollows. I am 

 indebted for it to Sir C. W. Wilson, K.C.B., F.R.S., to whom I had 

 mentioned the discovery, and from whom I received it after this 

 paper was in type. He tells me that it was on the slope, a few 

 yards from a wall boundary and pathway, and, as far as he can 

 remember, within a hundred yards of the garden wall of the Hotel 

 Continental (in the Boulevard Grandval). The dimensions are, at 

 a rough estimate, 5 y, Q feet. 



I saw from the vessel some granite blocks on the northern slopes of 

 a valley which comes down to the sea a little to the north of Ajaccio, 

 so I walked there next morning. They are not far from the 

 Penitencier de Castelluccio. Here, however, the blocks were not 

 so numerous or accessible, and I found but one good example of 

 these hollows, of which a diagram is annexed (Fig. 3) ; this occurs 



t^l^i'0\}\^^. 



Fig. 3. 



on the front face of a rudely quadrangular block, defined by rough 

 joints, which rises to a height of 9 or 10 feet above the ground, 

 being perhaps 5 feet wide near the top. In form the hollow 

 slightly resembles the outstretched head of a duck with a rather 



1 See Geol. Mag., 1869, PI. XVII, aud the Fig. on p. 486. 



^ In a specimen obtained from a block on a more exposed part of the hillside, in 

 which was one hollow, the cleavage -planes of the larger felspars still reflect light 

 fairly well. 



