402 Progress in Science. (July, 
supplemented this with a power half as great, he ventured to suggest, since 
the earth’s surface is thrown into folds which are proved, by fringing reefs and 
atolls, to be alternately rising and falling, that these movements might be 
explained, in part at least, as the effect of tidal movement in the earth itself. 
Stratigraphical Geology.—The line of demarcation between the Cambrian 
and Silurian rocks has ever been a source of dispute amongst geologists, 
according as they held to the views of Sedgwick, or adopted the classification 
of Murchison. When first the term Cambrian was suggested by Sedgwick, and 
the term Silurian by Murchison, these two observers had been working at 
different areas and independently, and subsequent researches demonstrated 
that some of Sedgwick’s higher Cambrian rocks were equivalent to Murchison’s 
lower Silurian rocks. The former first demonstrated that the only great break 
in the entire series occurs at the base of the May Hill Sandstone, or Upper 
Llandovery group, the lowermost bed of Murchison’s Upper Silurian. 
Murchison’s classification has, however, prevailed; it has been accepted by 
the majority of geologists, until the last year or two, when a tendency has 
sprung up to adopt the classification of Sedgwick, because the labours of 
geologists in Wales and in the Lake Distri& go to prove its truth. It may be 
observed that no base-line has existed for the Silurian system, that it has 
been constantly shifted to agree with the results of paleontological research, 
until nearly the whole of the old Cambrian system has been swallowed up in 
it by some writers. Professor Hughes recently observed, at a meeting of the 
Geological Society, that the bottom of the May Hill Sandstone constitutes the 
base of the Silurian system, and that the beds below, called Cambrian by 
Sedgwick, form a well-defined natural group, which, following the true 
principle of classification and justice to our nomenclature, we must adopt. 
The development of the Kimmeridge Clay in England, and its paleonto- 
gical contents, have formed the subject of an important paper by the Rev. 
J. F. Blake. He would divide the formation into two sections, attaining 
together in places a thickness of 650 feet. Professor Seely described a new 
Chelonian obtained from the Kimmeridge Clay, which he termed Pelobatochelys 
Blaket. 
Mr. Jukes-Browne has brought forward reasons for concluding that the 
Cambridge nodule-bed belongs to the base of the true Chalk Marl. This 
opinion is borne out by Mr. Whitaker from experience gained in mapping the 
Geology of the Cambridge district. 
The Geology of the Burnley Coalfield and of the country around Clitheroe, 
Blackburn, Preston, Chorley, Haslingden, and Todmorden, has been described 
in great detail in a memoir published by the Geological Survey, the work of 
Professor Hull and Messrs. Dakyns, Tiddeman, Ward, Gunn, and De Rance. 
The work contains a valuable list of the fossils by Mr. Etheridge, and a Cata- 
logue of all the works, numbering 561, that have been published to illustrate 
the Geology of Lancashire. 
Palzontologv.—F ossils indicative of a transitional zone between the Permian 
and Carboniferous strata were obtained at Spitzbergen by the late German 
Expedition. 
Mr. James Thomson has described some forms of corals from the carboni- 
ferous limestone of Scotland which he regards as new species and as belonging 
to three new genera allied to Clisiophyllum, which he names Rhodophyllum, 
Aspidiophyllum, and Kurnatiophyllum. The specimens are particularly inte- 
resting from the evidences of variation which they present. 
Dr. Dawson has noticed the occurrence of Eozoon canadense in Lower Lau- 
rentian rocks at Céte St. Pierre, on the Ottawa River. He referred particularly 
to the resemblance of weathered masses of Eozoon to Stromatoporoid corals. 
An interesting section of the Rhetic beds is being opened up on a line of 
ssailway in process of construction between Melton Mowbray and Nottingham. 
Prof. Huxley, in describing some new remains of Stagonolepis, observes that 
in outward form it resembled the existing Caimans of intertropical America, 
except that it possessed a long, narrow skull like that of a Gavial. 
Geologists’ Association.—At the Annual Meeting of this Association, held on 
