1870.] Geology and Palaeontology. 539 



Mr. Hopkins Method of Determining the Thickness of the 

 Earth's Crust. — Having been some time since challenged by M. 

 Delaunay,* a distinguished French astronomer and mathematician, 

 the late Mr. Hopkins' friend, Archdeacon Pratt, F.K.S.,t writes in 

 his defence and shows what he conceives to be a flaw in M. Delau- 

 nay's objections ; namely, that the earth is not a simple shell with 

 a fluid interior always revolving in one plane (in which case he 

 admits there would be no possible objection to M. Delaunay 's argu- 

 ments in favour of a comparatively thin rigid crust and a fluid 

 interior), but that it is ever being disturbed by the forces of pre- 

 cession and nutation ; and before the rigid crust and the fluid 

 interior could arrive at a state of equilibrium in one position, the 

 axis would begin to assume a new position, and the fluid interior 

 would again be unconformable in its motion to the external shell ; 

 and the earth's motion would again be retarded in a small degree, 

 sufficient to interfere with the axial variations to which the earth is 

 ever subject by the laws of precession and nutation. As science 

 advances it is absolutely imperative that in all these questions our 

 conclusions should be in accord with the laws of chemistry and the 

 known terrestrial conditions, as well as the laws of dynamics. 



A Neiv Fossil Snake in Greece. — A new fossil Python has been 

 lately described by Dr. Ferd. Eoemer % from the Island of Eubsea. 

 This is the second fossil ophidian found in Greece, and adds greatly 

 to the interest of the Miocene fauna of this old continent, already 

 rendered so important by the discoveries at Pikermi of such a 

 remarkable series of types of African Mammalia, together with the 

 Hipparion by M. Graudry. 



A Neiv Labyrinthodont Amphibian from the Goal-shale near 

 Neivcastle-upon-Tyne. — Mr. Thomas Atthey, well known to geo- 

 logists as one of the most indefatigable investigators of the fossil- 

 remains of the Newcastle Coal-shales, has again been successful in 

 bringing to light the skull of a new and remarkable Labyrinthodont 

 reptile, which the authors of the paper, § Messrs. Atthey and 

 Hancock, have named Batrachiderpeton lineatum. The lower jaw 

 was discovered three or four years since, but the cranium has only 

 now been obtained. 



It is impossible to contemplate the structure of the roof of the 

 mouth of this curious Labyrinthodont, without being reminded 

 of the arrangement of the parts in that of Siren, Proteus, and 

 Axolotl. The well-armed vomer in particular is very striking. 

 The extensive development of this vomerine armature and the 

 deficiency of bony maxillae, would seem to ally Batrachiderpeton 



■ * ' Geol. Mag.,' vol. v., p. 507. t Ibid., vol. vii., p. 421. 



% ' Abdruck a. d. Zeitscbr. d. Deutscben Geologiscben Gesellscbaft,' Jabrg, 

 1870. 



§ 'Ann. and Mag. Nat. Hist.,' Series 4, vol. vi., No. 31, p. 56, PI. I., July, 

 1870. 



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