40 Proceedings of the Royal Physical Society. 



are still covered with their epidermis. In no case have I 

 found two valves united. Several of the shells are perforated 

 by the whelk and the sponge Cliona. Some of the zoo- 

 phytes, Polyzoa, are attached to broken shells ; other mark- 

 ings are also seen on them like those on our present living 

 shells. Many of the shell fragments have their broken edges 

 rounded ; others, again, are as sharp as if only just broken. 

 This latter circumstance, I know, causes surprise, and often 

 difficulty to many. All this will vanish if those doubting 

 would collect shells on the present sea-shores ; they will find 

 that rounded and sharp fragments occur together, agreeing in 

 every respect with those found in the Boulder-clay. 



Most of the organisms of the Boulder-clay are still to be 

 found alive on our own shores, as may be seen by the 

 accompanying lists, — two only of the shells, viz., Astarte 

 arctica and Tellina proxima, being Scandinavian ; one alone, 

 viz., Trophon scalar i forme, being Arctic. The mode of 

 transport of the materials of the Boulder- clay, in all pro- 

 bability, has been ice, either by glaciers or icebergs. As I 

 wish only to introduce the organisms of its own age, I must 

 leave this part of the subject to others. 



I think it right to state that the whole of the shells have 

 been examined and named for me by J. Gwyn Jeffreys, 

 Esq., the sponge Geodia by Dr Bowerbank, both excellent 

 authorities ; therefore the list may be safely accepted as 

 correct. For the remainder I am answerable. 



The greater part of these organisms have been collected 

 by myself, assisted by my sons. All the species got by them 

 I have also found, and in no case have I admitted into the 

 list any specimen found in a doubtful position, always keeping 

 in view the human skull and rybat mentioned by the late 

 lamented Hugh Miller. Had I been inclined to do so, I 

 might have noticed the skull of an Arvicola, from the Wick 

 cliffs, found in a much less doubtful position than the human 

 one. I have taken only those dug out of the solid clay. The 

 whole of the specimens are in my possession, and I shall be 

 happy to show them to any one working in this field of 

 research. 



