Ryan and Hallissy — Some. New Fnssils Jrom Bruy Head. 247 



the problem will, we venture to hope, have a very great interest for Irish 

 geologists and for British geologists generally. 



On May 10th last year, one of the authors of this paper, searching for 

 Oldhamia near the well-known Brandy Hole, at the southern end of a shingle 

 beach at Bray Head, noticed on a huge boulder that had fallen from the cliff 

 face, the markings shown in fig. 3, Plate XXIII. The boulder was from a mass 

 of rock brought down in the previous February by a snow-slide. A minute 

 description of this fall of rock was given us by a Dublin and South-Eastern 

 Railway linesman on duty thereabouts, who, from the crash, was afraid injury 

 had been done to the permanent way, and making a hurried search was relieved 

 to find no harm had resulted. In the morning (the fall had taken place at 

 night) he saw what had happened — several tons of the clifi' face had been carried 

 away by the weight of snow that piled above it. The original site of the 

 stone block from which we were able, happily, to detach the fossil uninjured- 

 was easily traceable. It is represented in position by one of the bands of 

 hard green slate, just out of reach, which alternate with similar bands of 

 purple slate rich in Oldhamia, the whole forming a picturesque inset to the 

 hard green grits above and below. In thickness the slaty bands taken together 

 vary from 10 to 20 feet, thinning out as they dip about 45°N.W. towards the 

 Smugglers' Cave or Brandy Hole. Above, they disappear beneath the Boulder- 

 clay, through which, here and there, the purple slates protrude. At the 

 northern end of the shingle beach a similar thickness of purple slate is inter- 

 bedded with the grits, but, judging from the dip and other field observations, it 

 is unconnected with the beds that we have worked. All the rocks here possess a 

 more or less well-marked slaty cleavage, and bear abundant evidence of having 

 undergone considerable crushing and movement. 



The specimen illustrated in fig. 3, Plate XXIII, was sent to 

 Mr. r. E. Gowper Pteed, of the Sedgwick Museum, Cambridge, who very 

 kindly gave a provisional opinion on it, and with equal kindness allows us to 

 make use of that opinion in our paper. " I believe," he says, " that both objects 

 on the slab are portions of the head-shield of a large trilobite. One seems 

 to be able to detect the glabella, a wide preglabellar portion, the marginal 

 furrow, and a broad flattened border. Whether a facial suture is present 

 is rather doubtful, but it is certainly suggested on one side of the specimen. 

 The glabella seems to be unfurrowed, and if the real base of the head-shield 

 coincides with the termination of the specimen, the glabella would be about 

 three-fifths the length. There is a curious concentric depression in the pre- 

 glabellar area, but not so sharp as the marginal furrow. The ornamentation 

 consists of small punctae, which are in some relation to the curious radial 

 striation, which latter, however, seems to be a secondary structure and not 



