Intelligence and Miscellaneous Articles. 229 



much stress), has, with the aid of Profs. Geinitz and Liebe and Dr. 

 von Hauer, investigated tbe subject independently, both by exami- 

 nation of sections in the field, and by the study of the evidence 

 preserved in the Museums, especially those of Dresden, Vienna, and 

 Freiberg. The sections described in this paper are from: — (1) 

 Silesia (Ostran), in which Dr. A. Dittmarsch is followed ; (2) Murane 

 (Saxony) ; (3) Northern Thuringia. Those in the districts (2) and 

 (3) are from the author's own observation last summer. The strati- 

 graphical evidence shows that there is a very marked break in time 

 between the Zechstein and the Bunterschiefer of Murchison, which 

 he included in the " Permian System." Almost every kind of dis- 

 cordance that can possibly occur between two successive series of 

 strata is shown to occur in Central Europe between the Dyas and 

 Trias, and in particular between the Bunter and the Zechstein ; 

 physical and stratigraphical evidence therefore confirm the classifi- 

 cation adopted by Geinitz on palaeontological grounds. 



The meaning of the name " Dyas," which has become well esta- 

 blished abroad, was illustrated, since it is often overlooked by English 

 geological writers ; and a dyassic order was pointed out as existing to 

 some extent in the English series. 



Some general reasons, based on the physical characteristics of the 

 Dyas-group, were given for regarding it as much more closely allied 

 to the preceding Carboniferous than to the succeeding Trias. 



The last portion of the paper was more speculative, and in it an 

 attempt was made to trace, in the facts we know of the geology of 

 Central Europe, and the inferences drawn from them, the causes of 

 the apparent anomaly between the fauna of the Post-Carboniferous 

 strata of more northern Europe and that of the Alpine Trias. 



XXXI. Intelligence and Miscellaneous Articles. 



ON THE ELLIPTICTTY OF PLANETS. BY L. d'aURIA, LATE 

 GEODETICAL ENGINEER OF THE ITALIAN ARMY*. 



4 DMITTINGr that planets were originally in a fluid state, how- 

 "- ever heterogeneous their respective masses may be considered, 

 their form of equilibrium, when fluid, must have been such that the 

 direction of the resultant of all the forces acting upon any point of 

 the free surface must have been normal to the surface itself. Now 

 the form of equilibrium of any fluid mass when at rest is the sphere ; 

 and when any fluid sphere is made to revolve around any one of 

 its diameters, it becomes more or less flattened on its axis of rota- 

 tion on account of centrifugal force. This causes the sphere to 

 become an oblate ellipsoid, whose minor diameter coincides with 

 the axis of rotation itself ; and therefore the equation of any meri- 

 dian line on the surface of any fluid mass revolving around an axis 



* Communicated by the Author. 



