266 Proceedings of the Royal Physical Society. 



Section No. 1 sliows the unconformable patch of newer palaeozoic rock 

 near Ballenstedt on the south side of the great fault, and the position of the 

 Mansfeld basin at the S. E. extremity of the range. 



No. 2 shows the general structure of the Lower Harz and Kyffhauser. 



No. 3 indicates the probable unconformability in the Secondary series at 

 Wernigerode, the relations of the rocks in the Elbingerode district, and the 

 position of the Permian volcanic masses at Ilfeld. 



No. 4 shows the unconformability below the upper chalk on the north 

 side of the great fault, the relation of the granite of the Brocken to the faults, 

 the position of the silver veins of Andreasberg, and the relations of the 

 Permian rocks on the soutliern flank of the Harz. 



No. 5 illustrates the structure of the portion of the West Harz between 

 Goslar and Seesen. The great inversion of the Rammelsberg is shown on the 

 east, and the Culm greywackes and shales are seen overlying the Upper 

 Devonian beds on the western side of the Innerste Valley. The Kersantite 

 dyke of Lautenthal is seen piercing the Culm, and altered in position by one 

 of the faults. 



XIX. On the Classification of Animals. By J. COSSAR 

 EwART, Esq., M.D., Eegius Professor of Natural 

 History in the University of Edinburgh. 



(Read 20th February 1884.) 



Until comparatively recent years naturalists chiefly con- 

 cerned themselves with drawing up definitions of animals, 

 and with elaborating systems of classification. The arrange- 

 ment usually adopted was extremely unnatural, for the 

 systematists trusted either to external characters or to very 

 simple combinations of characters. In course of time, how- 

 ever, great advances were made — the internal structures 

 were taken into consideration, so that when a new era was 

 introduced by the appearance of the " Origin of Species " in 

 1859 an almost perfect natural system of classification had 

 been devised, and it seemed as if the theory of descent with 

 modifications had been unconsciously used in making the 

 arrangements, " and not some unknown plan of creation, or 

 the enunciation of general propositions, and the mere putting 

 together and separating objects more or less alike." Until 

 the time of Cuvier naturalists were bent upon establishing 

 one continual uniform series to embrace all animals between 

 the links of which it was supposed there were no unequal 

 intervals. But even after Cuvier's time the old traditions 



