ANNIVERSARY ADDRESS OF THE PRESIDENT. IxXXvil 



are every day increasing and call for the most careful investigation ; 

 for, though it is easy to adopt the notion of species hving over, as it 

 were, some catastrophe which had destroyed others, it is not so easy 

 to explain why such species should have disappeared and then reap- 

 peared, the strata not even admitting the explanation in this case hy 

 a recurrence of the same physical conditions. Investigation proves 

 the fact, and I imagine, as no one will probably advance the theory 

 of a second creation of the same species, that the appearance of the 

 same species in two formations geologically separated in time must be 

 taken as a strong argument for believing that, though locally de- 

 stroyed, the species had still continued to exist in other regions, the 

 harmony of which had not been similarly disturbed, and hence that 

 the unity of the creation has never been entirely broken up. The 

 importance of the fossil evidence may be understood from the sum- 

 mary of the species described given by the author ; thus, combining 

 the Spirifer-sandstone and the Orthoceratite-schist into one group 

 — the lower, the Stringocephalus-limestone and Cypridina-schist 

 into another — the middle group, and taking the Posidonomya- 

 schist as the upper group, 107 species occur in the lower group, 

 225 in the middle group, and 24 in the upper, in addition to 8 

 species which are common to the lower and middle groups. In 

 addition to the very able discussion of the fossil evidence, there are 

 many very interesting particulars in the work : such, for example, as 

 the careful discrimination of the physical conditions of the deposits 

 from the general relations of the fossils and their natural habitats, 

 and the chemical comparison of metamorphosed with unmetamor- 

 phosed nodes, a species of comparison I have indeed at a former 

 period suggested, in reference to the general question of metamor- 

 phism, but which is here made subservient to the recognition of the 

 former metamorphosed strata in the present unmetamorphosed. As 

 regards the geological comparison of the Nassau deposits with those of 

 other countries, I cannot deny myself the pleasure of preserving the 

 observations of Mr. D. Sharpe. He observes : — 



The completion of the work of the two distinguished brothers, Dr. 

 Guido and Dr. Fridolin Sandberger, on the Devonian fossils of 

 Nassau*, will be hailed with satisfaction by all palaeontologists : the 

 accurate descriptions and figures which it gives us of the species of 

 organic remains of Nassau, with distinct reference to the beds in which 

 they are found, will prove of great help to us in unravelling the still 

 only half-solved problem of the order of geological succession of the 

 various deposits constituting the Devonian system. As the principal 

 portions of the palaeontological part of the work were published in 

 past years and have already received due mention from Mr. Hamil- 

 ton, I shall confine myself to an examination of the appendix which 

 contains the authors' comparison of the palaeozoic formations of the 

 Rhenish Provinces with those of other countries, in which we are 

 naturally most interested, more especially in regard to their remarks 

 on Devonshire, and on the analogous formations of Belgium and the 



* Die Versteinerungen des Rheinischen Schichtensy stems in Nassau. 

 4to. Wiesbaden, 1850 to 1856. 



