Vice-President's Address. 137 
Productus semireticulatus, Martin. 
.. scabriculus, Martin. 
Edmondia rudis, M‘Coy. 
Schizodus sp., allied to S. carbonarius, Portl. 
Modiola lingualis, Phill. 
Anthracosia Urei, Flem. 
Leda attenuata, Flem. 
Gontotites sp., allied to G'. excavatus, Phill. 
An LKuomphalus was also got, but was unfortunately 
destroyed before I saw the collection. 
Leaving out of consideration those individuals which are 
only generically identified, two of the species, Modiola 
lingualis and Leda attenuata, have been recorded from the 
upper beds of the Calciferous Sandstone Series; P. semireti- 
culatus, P. scabriculus, and Edmondia rudis are frequent in 
the Carboniferous Limestone Series of Scotland; while 
Anthracosia Urei is generally restricted to the Lower Coal- 
Measures. Anyone judging of the age of these rocks from 
the Molluscan remains, would, without doubt, class them as 
Lower Carboniferous, whereas they are certainly of Upper 
Coal-Measure age. 
This case is not an isolated one, and Dr John Young has 
referred to such occurrences in his paper entitled “ Notes on 
the Occurrence and Range of Lingula in the Carboniferous 
Series of the West of Scotland.”+ Speaking of the apparent 
extinction and reappearance of an organism in a higher 
horizon, the paper concludes with the following remarks :— 
“Of such changes we have evidence in several of our coal 
seams, formed of the remains of a terrestrial vegetation 
accumulated in swamps at or near the sea-level, and now 
found to be overlaid by a great thickness of fossiliferous 
marine strata. But wherever we find a sudden extinction of 
the organic life in any stratum, we are not to suppose that 
such extinction was universal. In most cases it must have 
been comparatively local, for a total extinction would imply 
a new creation of the same forms in every succeeding age of 
strata in which they are met. The most probable supposi- 
tion is, that during all the long geological ages in which our 
1 Trans. Geol. Soc. Glasgow, vol. ii., p. 144. 
