ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixv 



confusion that prevailed is instanced by the state of knowledge and 

 nomenclature of some 22 species that were best known before. Of 

 these 5 were placed in 2 genera, 3 in 5 genera, 2 in 4, 1 in 3, 1 in 6, 

 1 in 7, and I in 8 different genera. Among the species, 4 had re- 

 ceived 2 names, 4 others 3 names, 1 four, 3 five, 2 six, 1 seven, 

 1 nine, 2 ten, and 1 eleven names ; so that out of 22 true species of 

 Nummulites no fewer than 98 reputed ones had been constructed ! 



M. d'Archiac divides the history of the study of Nummulites into 

 five epochs. The first, or fabulous period, and by far the longest 

 though of least importance, commenced with the writers of antiquity, 

 and, after a long interruption during the middle ages, was resumed 

 after the middle of the sixteenth century to extend into that of the 

 eighteenth. The second period, more scientific than the first, but 

 scarcely nearer the truth, extended from 1770Jto 1804, when the 

 sagacity of the illustrious Lamarck commenced to shed a new light 

 on the affinities of the lower animals. The third period, from 1804 

 to 1825, was marked by numerous attempts towards a classification of 

 the Rhizopoda, and Nummulites were described and figui'ed with 

 considerable care, the opinion of their Molluscan and Cephalopodous 

 position prevailing in the writings of naturalists. The fourth epoch 

 extended from 1825 to 1835, when zoologists seem to have settled 

 into a fixed faith about the affinity of Nummulites and Foraminifera 

 with Nautili and Cuttle-fishes (the doctrine taught two hundred and 

 sixty years before by Conrad Gesner), and directed their attention 

 closely to the structure and minuter classification of these curious 

 bodies. It was marked by the commencement of the extensive 

 labours of Alcide d'Orbigny among the Foraminifera. The fifth and 

 final epoch commenced with the notable discovery by F. Dujardin of 

 the low and Amoeboid nature of the animal of the Rhizopod, and is 

 signalised by numerous and excellent researches into the features and 

 forms of existing and extinct Foraminifera. At length these living 

 problems may be said to be understood, and the monograph by M. 

 d'Archiac himself fitly closes their history for the present. 



The high geological value to which the Nummulites and their order, 

 the Rhizopoda, have speedily attained during the last fifteen years, 

 contrasts curiously with the degradation they have as rapidly under- 

 gone during the same period in zoological position. Before 1835 

 they were generally regarded as Cephalopoda, and naturalists of 

 repute were not wanting who went so far as to describe even the 

 parts of the minute cephalopod that constructed the foraminiferous 

 shell. That they were not Mollusca was scarcely suspected, though 

 half a century before their lower nature had been, on slender grounds 

 however, often maintained. The assumption of their elevated zoolo- 

 gical position led to many an argument against support of the theory 

 of the prevalence of a warm climate during the ante-tertiary epochs, 

 from the fact of the abundance of chambered cephalopods in the 

 ancient sea-beds of now cold or temperate latitudes. The abundance 

 of minute chambered Cephalopoda in the North Atlantic at the pre- 

 sent time, and their almost universal distribution, were confidently 

 appealed to as conclusive against the inference. Their number in 



VOL. X. e 



