90 " Proceedings of the lioyal Physical Society. 
of Scotland. The limpet, and samples of some more speciehi 
of shell, are to be picked up. One of them {Tapes decussata) 
claims special notice. Its remains hold the fifth, if not a 
higher place, in the shell mound at Brigzes. It is not 
known to exist now in the Moray Firth ; and (upon the best 
possible* authority on such matters) the most northerly lo- 
cality where it is now found alive is the coast of Carnarvon- 
shire. It seems to form a striking exception to the rule. 
While the other species, that are now extinct on our shores, 
are withdrawing to the north, and are found alive only 
towards the Arctic Circle, this species, once frequent, bat not 
now known with us, has withdrawn in the opposite direction 
— to a warmer latitude. 
There is evidence enough in these mounds, and of a like 
nature as that drawn from the Danish accumulations, to show 
that they have been the work of man, and not the efifect of 
any tidal current, or of any other natural cause. The shell- 
fish which these remains represent are, with scarcely an ex- 
ception, edible, and continue to this day to be eaten. In all 
deposits by the sea there is abundance of species that have 
ever been rejected as food. The shells are full-grown or adult 
shells. In collections made by the sea, the young animals 
are abundant, and often predominate. 
Now, no movements of wind or water could have thus se- 
lected the edible and the adult, and .left behind the noxious 
and the young. They must have been gathered by man, 
and for the purpose of supplying his wants. Many other 
arguments have been brought forward to prove this, so that 
there is now no doubt entertained about the matter. One 
strong proof is, that the oyster and the periwinkle are never 
found living and mingled together in the same part of the 
sea. The former exists between tide marks, the other in 
deep water. The cockle delights in sand ; the mussel must 
be moored to a rock or hard bottom. In different parts of 
the masses of shells at Brigzes, there are to be seen many 
stones that have been subjected to considerable heat. They 
probably have been used in this state for cooking, as is 
known to be the case among people of primitive habits to 
* Eobert M' Andrew, Esq., London. 
