1875.| Geology. 117 
The study of the fauna and flora of these different formations in different 
distri@s yields somewhat discrepant results; and there appears to be no 
alternative but to accept the conclusion that a Tertiary flora was contem- 
poraneous with a Cretaceous fauna, establishing an uninterrupted suc- 
cession of life across what is generally regarded as one of the greatest breaks 
in geologic time. 
Palgontology.—Mr. L. C. Miall presented to the Geological Section of the 
British Association at Belfast, a Tabular View of the Classification of the 
Labyrinthodonta, which was divided into ten sections. Forty-two genera and 
126 species are now known. Some of these animals, in their mode of life, 
appear to have been fish-like. Some resembled serpents, others crocodiles, 
whilst those of Kilkenny appear to have been salamanders. 
Mr. Waterhouse Hawkins has recently expressed his opinion that the 
Iguanodon was a marsupial animal. 
Remains of the Lemming have been found in lacustrine brick-earth at 
Salisbury, associated with bones of the Mammoth. 
Prof. Rupert Jones records the occurrence of Gyrogonites (fossil seed-vessels 
of Chara) in the London clay of Islington. He also adds Cythere plicata to 
the known fauna of the London clay. 
Lythology.—The study of rocks has of late become a popular one, and many 
important observations have been made. 
A detailed examination of the Cumbrian ash-rocks has convinced Mr. J. 
Clifton Ward that, in many cases, most intense metamorphism had taken 
place, that the finer ashy material had been partially melted down, and a 
kind of streaky flow caused around the larger fragments. There was every 
transition from an ash-rock, in which a bedded or fragmentary stru@ture was 
clearly visible, to an exceedingly close and flinty felstone-like rock, undistin- 
guishable in hand specimens froma true contemporaneous trap. Such altered 
rocks were, however, quite distinc in microscopic structure from the undoubted 
lava-flows of the same distri@, and often distiné also from the Welsh 
felstones, falthough some were almost identical (microscopically) with the 
highly altered ashes of Wales, and together with them resembled the 
felstone-lavas of the same country. This metamorphism among the Cum- 
brian rocks increases in amount as the great granite centres are approached; 
and it was believed by the author that it took place mainly at the com- 
mencement of the Old Red period, when the rocks in question must have been 
buried many thousands of feet deep beneath the Upper Silurian strata; and 
when probably the Eskdale granite was formed, perhaps partly by the extreme 
metamorphism of the volcanic series during upheaval and contortion. The 
author stated his belief that the Cumbrian volcanoes were mairly subaérial, 
since some 12,000 feet of ash and lava beds had been accumulated without 
any admixture of ordinary sedimentary material, except quite at the base, con- 
taining scarcely any conglomeratic beds, and being destitute of fossils. He 
believed also that one of the chief vclcanic centres of the distri@ had been 
the present site of Kenwick, the low craggy hill called Castle Head repre- 
senting the denuded stamp or plug of an old volcano. 
Prof. Hull has described the microscopic structure of a porphyry from the 
Island of Lambay, a few miles to the north of Dublin Bay. The order in which 
the different minerals seem to have been formed is as follows :—First, during 
consolidation, the crystals of orthoclase ; next, the crystalline grains of mag- 
netite ; and lastly, the felsitic base itself. Then, after consolidation, chlorite, 
calcite, and pyrites. 
Researches upon the thermal condu@tivity of certain rocks have been made 
by Prof. A. S. Herschel and Mr. G. A. Lebour. Among these, granite has 
been found to offer the least resistance to the passage of heat, and coal the 
greatest. Shale comes next below coal; but between these two and basalt 
there is a gap of considerable extent. Between basalt and granite come all 
the other rocks examined, including a number of limestones and sandstones of 
different varieties. 
