THANSACTIOXS OF THE SECTlOXi^, 89 



fi'om the present form of our globe what was its form when it solidified. lu so far 

 as tidal retardation can show to the contrary, its form, when solidification took 

 place, may have been as oblate as that of the planet Jupiter. 



There is another circumstance which must be taken into account. The lowering 

 of the equator by the transference of the materials from the equator to higher lati- 

 tudes must tend' to increase the rate of rotation, or, more properly, it must tend to 

 lessen the rate of tidal retardation. 



On the Variation in Thickness of the Middle Coal Measures of the Wigan 

 Coal-field. By C. E. De Range, F.O.S., of H.M. Geological Survey. 



From the Arley Mine, the lowest coal-seam of this series, to the Tnce-Yard Coal, 

 at Worthington, north of Wigan, the measures are 2200 feet in thickness, thinning 

 50 feet per mile to the S.W. to Prescot, where the measures are only 1445 feet in 

 thickness, and 57 feet per mile to the N.E. towards Burnley, where the measures 

 between the equivalents of these coals are only 1000 feet in thickness — proving 

 the Wigan coal-basin to be not merely a synclinal of subsidence, but one of deposition, 

 the axis of which was shown to have gradually travelled northwards in time from 

 the district of St. Helens to a point north of Wigan. The importance of arranging 

 colliery sections in a definite geographical direction, and the importance of noting 

 the occurrence of very thin coal-seams and horizons of fire-clay and of seams full of 

 Anthracosia, were insisted on as means of identifying equivalent coal-seams across 

 a district. Great lateral shifts were shown to have occmTed between many of the 

 great N.N.W. faults which traverse the Wigan district and divide it up into a 

 series of belts. 



On Lahyrinthodont Remains fro77i the Upper Carboniferous (Gas- Coal) 

 of Bohemia. By Dr. Anton Feitsch, 



The beds of gas-coal which are now being worked at so many localities, both in 

 Europe and America, serve not only to illuminate our chambers, but to throw fresh 

 light upon many branches of pal8eontoloo;ical science ; for these beds of gas-coal 

 have been found to yield a remarkably fane -fauna, especially rich in the remains 

 of Labyrinthodonts, fishes, and insects. 



During the last five years, I have been so fortunate as to discover in Bohemia 

 two localities which afford us beautifully preserved relics of ancient life thus en- 

 tombed in the gas-coals. 



One of these localities is Nyran, near Pilsen, in the western part of Bohemia ; the 

 other is Kounova, near Kakonitz, in the north-west of the country. 



In both of these places the gas-coals are found to be situated on the top of the 

 Coal-measures proper, but beneath the true Permian deposits. The plants of these 

 beds are closely allied in character to those of the Coal-measures ; but the animals 

 appear to be of Permian types. 



I do not intend upon the present occasion to enter into a full enumeration and 

 description of these interesting fossils ; but I take the liberty of submitting to this 

 Section of the British Association series of specimens of casts and of plates of some 

 of these fossils which I have brought to this country for the purpose of comparing 

 them with the similar remains found in the British Coal-fields. 



The first three plates exhibited contain enlarged drawings of very small Laby- 

 rinthodonts of the gi'oup called by Prof. Huxley JNIicrosauria. One of these, not 

 more than one inch (?) long, has the skeleton completely ossified. 



The fourth and fifth plates are devoted to a large species of Luhjrinthodmi of 

 about 5 feet in length. 



Among the specimens, the author drew attention to the teeth of a Ctenodm, of 

 ■which species the bony parts of the skull were found preserved. 



Of the remarkable genus Diplodm a lower jaw with teeth served to show that 

 these latter are not, as was formerly supposed, the dermal spines of a Kay. 



Among the insect-remains was observed a new species of Gatnsom/chm, speci- 

 mens of which cover the whole surface of some slabs of the rock. The restored 



