1868. | Geology and Palxontology. 577 
now, only a second representative was known, namely, from the 
Miocene beds of Java. 
The Report of the Dundee Meeting of the British Association 
has been issued during the past quarter; but we need only state 
that it contains the third Report of the Committee for exploring 
Kent’s Cavern, Devonshire; and Mr. Henry Woodward’s third 
Report on the Structure and Classification of the Fossil Crustacea. 
Professor Heer’s great work on the Miocene Flora of the Arctic 
regions* has been published within the last few months. A synopsis 
of its contents would be identical with the account of his paper read. 
before the Royal Dublin Society, which we gave in a former 
Chronicle. 
The absolute duration of geological time is a question which is 
now exciting the attention of physicists and geologists, owing chiefly 
to Mr. Croll’s numerous papers bearing more or less directly on the 
subject. In the May and August numbers of the ‘ Philosophical 
Magazine’ are two instalments of a paper by him “On Geological 
Time, and the probable Date of the Glacial and the Upper Miocene 
Period ;” but we shall reserve our record of his conclusions until its 
completion. From another point of view Mr. Geikie has computed, 
in a paper in the ‘Geological Magazine’ for June, that “such a 
continent as Europe will, at the present rate of subaérial waste, be 
worn away in about 4,000,000 years.” 
The only other paper in the ‘Geological Magazine’ for the 
quarter which we have space to notice is one by Mr. Davidson, 
“On the Earliest Forms of Brachiopoda discovered in Britain.” In 
the lowest beds of the Lower Cambrian (Sedgwick) there are no 
Brachiopods; in the Harlech Group above is a Lingulella, which 
passes up into the overlying Menevian Group, or Lower Lingula 
Flags, and is associated probably in the former, and certainly in the 
latter, with a Discina and an Obolella. The genus Orthis also 
makes its first appearance in the Menevian beds. In the Middle 
Lingula Flags we have Lingulella, Lingula, and Kutorgina (Obo- 
leila) ; and in the upper beds, in addition to a species of each of 
those genera, there occurs another Orthis. In the upper division 
of the Primordial zone (Tremadoc slates) the same genera occur, 
with the exception of Orthis, which, however, becomes abundant in 
the Lower Llandeilo. This paper is an interesting contribution to 
the facts relative to the first appearance of life. 
* Flora fossilis arctica. Die fossile Flora der Polarlander; von Dr. Oswald 
Heer. Mit einem Anhang iiber versteinerte Holzer der arctischen Zone, yon 
Dr, Carl Cromer. 
PR 
