1868.] Geology and Paleontology. 407 
jurensis. The richness of the upper zone contrasts very strongly 
with the poverty of the lower, the species yielded by the whole 
formation numbering 122, of which only thirteen belong to the 
zone of Ammonites gigas, four of them being common to both. 
Twenty-six species are common to these beds and the lower zones 
of the “ terrain Kimmeéridien,” and twenty-two occur in the Lower 
Portlandian of the Boulonnais, while only four are common to them 
and the Upper and Middle Portlandian. To the Lower Portlandian, 
therefore, the authors refer the two zones of the Yonne forma- 
tion. M. Cotteau, who has contributed the geological portion of 
this excellent monograph, records that the Neocomian beds are found 
reposing sometimes on the zone of Ammonites gigas, and sometimes 
on that of Pinna suprajurensis. From this fact he infers the 
existence of a stratigraphical break or unconformity between the 
two formations. M. de Loriol, however, from a paleontological 
standpoint, regards these two zones as two facies of the Portlandian, 
inferrmg that in the west of the Yonne district circumstances 
favoured the deposition of the zone of Pinna suprajurensis, or, in 
other words, the existence of its rich fauna, while in the remainder 
the more scanty population of the zone of Ammonites gigas could 
alone flourish. Similarly with the Neocomian, which at Bernouil 
is represented by the remarkable zone of Peltastes stellulatus, 
covering the Portlandian beds in that area, while at Auxerre the 
latter are succeeded by the ordinary marls and yellow limestones of 
the Lower Neocomian formation. M. de Loriol also remarks that 
the division between the Cretaceous and Jurassic series appears to 
be less decided in the Alpine area than in any other. 
In a paper on the classification of certain Fossil Corals, published 
in the recently issued volume of the ‘ Philosophical Transactions’ 
for last year, Dr. Duncan comes to the conclusion that the genus 
Palzocyclus must be abolished, and that its species must be added 
to the genus Cyathophyllum. Thusa representative of the Tertiary 
coral-fauna is removed from the Paleozoic. The author also shows 
that the genus Battersbya does not belong to the Mzlleporidz, but 
should be associated with the formerly solitary genus Heterophyllia 
in a division of the Astraid#. Thus two genera with Mesozoic 
affinities are introduced into the Paleozoic coral-fauna, 
On March 12th Mr. J. A. Phillips read a paper before the Royal 
Society on the “Chemical Geology of the Gold-fields of California.” * 
He infers that quartz-veins have generally been produced by the slow 
deposition of silica from aqueous solutions, that their formation is 
due to hydrothermal agencies, and that the silica may have been 
slowly deposited at low temperatures. The author also speculates 
on the cause of the presence of gold in the same solution, and sug- 
* ©Proceedings of the Royal Society,’ vol. xvi., No. 100, p. 294. 
VOL. V. 2F 
