68 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
life, he was, however, what he called a “ Zoo-Geologist,”’ 
working on the border-line of the two sciences and throwing 
light on both, bringing zoological knowledge in regard to 
the animals represented by the fossils to bear upon geological 
problems, and showing on the other hand how geological 
changes in the past help to explain the distribution of animals 
and plants at the present day. In some respects this was 
the finest and most original work that he ever did. During 
this period he was one of the founders of the Paleeontographical 
Society, which has issued a noble series of volumes, some of 
the earlier of which (e.g., British Tertiary Echinoderms) are 
Forbes’ work. He also contributed largely to other geological 
publications. : 
We can only mention two of the more important of these 
pieces of work. One of these was his careful investigation 
of the layers of supposed Wealden rocks, known as the 
Purbeck beds. In the autumn of 1849 he went down to the 
coast of Dorset and spent some months making a most minute 
investigation of the strata, with the result that he proved 
that these beds really belong to the Oolitic series. Sir Archibald 
Geikie tells us that, “with magnifying glass at eye he crept 
over the faces of the rock, layer by layer, noting the peculiarities 
of each from top to bottom. As the result of this detailed 
scrutiny, while there was no evidence that any physical 
disturbance had taken place in the area during the deposition 
of the whole of the strata, the testimony of the included fossils 
revealed a remarkable series of alternations of fresh, brackish, 
and salt-water conditions over this part of England when the 
Purbeck group was in course of deposition. Our naturalist 
made the further important discovery that on several separate 
horizons these strata enclose the shells of some living genera 
of air-breathing mollusks—creatures which had not till then 
been found in so ancient a formation. It was characteristic — 
alike of his humour and of his habit of making fun of his 
