342 Proceedings of the Royal Physical Society. 
survived these changes, and is now directly—one might 
almost say, unconformably—surmounted by a deposit of 
sand and loam, which, for aught one could determine to the 
contrary, may well have been laid down entirely since the 
days of the Romans. 
We may now notice the shells as they actually occur. We 
find, as might be expected, more or less of a mixture of species 
here. There are some shells which have travelled downwards 
from the beach under the influence of gravitation; some 
again which have been washed up from lower laminarian 
zones during storms; some few which may have drifted down 
stream from muddy or rocky bottoms higher up the Forth. 
With these there is a fairly-large percentage of shells which 
lived on the spot. Looking at the assemblage as a whole, 
what must strike the observer is the small percentage of 
carnivorous Mollusca as compared with the abundance of both 
individuals and species of the forms that are vegetable feeders. 
Even though an abundant food supply would easily be 
obtained on the spot, the only indigenous siphonated gastero- 
pods were a small number of Purpura lapillus, a fairly large 
percentage of small examples of Nassa incrassata,a few of 
Trophon truncatus, and three examples of Murex erinaceus. 
Not a single example of Fusus antiquus, and only some 
evidently-drifted shells of Buccinum undatum, were met 
with. 
Of the holostomatous Gasteropoda there were seen examples 
of Lnttorina littorea, which may have rolled downward from 
the beach; some few of L. obtusata and L. rudis; one speci- 
men of Lacuna divaricata, which may have drifted hither on 
seaweed. With these, and probably brought here in the 
same manner as the last, were several examples of Rissoa 
striata and Hydrobia ulve. As might have been expected, 
Patella vulgata occurs in more or less abundance, but as the 
deposit is mainly sandy, the examples met with are almost 
certain to be drifted. Patina pellucida probably came with 
floating seaweed, as may also the example of Tectura testu- 
dinalis. Trochus cinerarius is common. Two specimens of 
Aporrhais pes-pelecant were met with. No specimens of 
Natica were seen, although J. catena is known to occur on 
