ANNIVERSARY ADDRESS OF THE PRESIDENT. lix 



.Cf and H is more or less closely connected in all classes of fossils 

 with the former phases of this fauna contained in the underlying 

 etages E and F. 



2. Notwithstanding certain general connexions between these 

 same upper etacjes, G and H, of the basin of Bohemia and the three 

 great Devonian subdivisions, there is no such affinity between the 

 faunas of the two formations as would justify our considering them 

 as representing, under different appearances, contemporaneous de- 

 posits. And with regard to the apparent paradox that the " faune 

 troisieme " during its later phase, nearest in point of time to the 

 Devonian fauna, is less closely connected with it than with the 

 lower etages E and F, he observes that his investigations prove that 

 each class of fossils shows a greater or less number of specific 

 connexions, without counting the constant generic connexions be- 

 tween the etages E and F and the overlying Gand H; and consequently 

 that, in a palaeontological point of view, the etages G and H completely 

 maintain their Silurian character, and are only associated with the 

 Devonian beds by those ordinary points of resemblance which occur 

 during any given geological epoch to announce the following period. 

 I have already pointed out the object of the second portion of this 

 work ; but I cannot take leave of M. Earrande, to whom I fear I 

 have hardly done full justice, without making one observation. 



"Whether the colonial theory of M. Earrande be right or wrong, 

 it is impossible not to see in all his observations a confirmation of 

 that argument which has often been supported in this room, and to 

 which I have myself more than once ventured to allude, viz., that 

 in formations of the same age, although separated geographically by 

 greater or less distances from each other, we must not expect to find 

 the same species or even genera always appearing at any given 

 geological horizon simultaneously. The various conditions of life, 

 the depth of the sea, the difi'erent proportions of calcareous or 

 siliceous or argillaceous elements in the deposit, must have pro- 

 duced a difference in the organic contents of the formation — a 

 difference which may often have shown a greater intensity in neigh- 

 bouring regions than in such as are separated by greater distances 

 in space. The difference caused by distance in time has always 

 been appreciated by geologists ; but that caused by distance in space 

 has sometimes been overlooked, not so much perhaps of late years as 

 formerly, when the identity or non-identity of fossil contents was 

 looked upon as the all-sufficient reason for synchronizing or sepa- 

 rating formations occurring at a considerable distance from each 

 other. 



Amongst the more important discoveries of last year I must 

 notice that of Professor Huxley, who, in examining some reptilian 

 remains found in the Kilkenny Coal-field, ascertained the exist- 

 ence of not less than six genera, five of which are certainly new, 

 while the sixth, according to Profesor Huxley, may or may not be 

 identical with the AntJiracosaurus of the Scotch Carboniferous rocks. 



