38 



about one foot in seven to the north-west. The author found only 

 a single specimen of a petrified vegetable with the fishes. It was 

 the leaf of a canna or a reed. 



The Orkney Islands have much uniformity in their geological 

 structure. The principal rock is this sort of slate, which is connected 

 with sandstone, and has occasionally interposed thin beds of lime- 

 stone, that seldom contain any organic remains. 



The only primitive rocks in Orkney are in a limited district around 

 Stromness, and in the contiguous small island of Graemsey. There 

 granite, and gneiss approaching to mica-slate, appear in the surface, 

 and have resting on them a coarse sandstone conglomerate. This 

 last is in immediate contact with the slaty rock described above. 

 The highest ridges in Orkney are the mountains of Hoy, which are 

 composed of thick beds of sandstone, in which the author lately 

 discovered a vast bed of trap. This sandstone, as well as that which 

 occurs in the other islands, belongs to the old sandstone ; and the 

 slaty rock is probably a newer part of the same formation. 



There are not any distinct traces either of the mountain limestone 

 or of the coal formation in Orkney, unless we are disposed to con- 

 sider this slaty rock as the oldest member of the moimtain limestone. 

 But from its connexion with the sandstone, it is safer to reckon it a 

 member of the old red sandstone series. 



Specimens were exhibited to the Society illustrative of the author's 

 statements. 



4. Notice of further DiscoverieB at Burdiehouse. By Dr 



Hibbert. 



The author announced that, since his former paper was read, on 

 the organic remains of the limestone quarry at Burdiehouse, dis- 

 coveries of still greater interest had been made. These chiefly con- 

 sist of the remains probably of a large animal of the Saurian tribe, 

 namely, what appears to be the epiphysis of one of the vertebrae, 

 presenting, when broken across, the cancellated structure of bone — 

 several large scales obtained by Mr ConneU, — and, in particular, a 

 large and beautifu.lly perfect tooth, two inches and a quarter long, 

 and covered with its enamel, which is quite entire. The remains 

 here alluded to were exhibited and presented by the author and Mr 

 ConneU to the Society's Museum. 



