iviii. PRESIDENT'S ADDRESS. 



classification is represented by three principal groups, each one of 

 considerable duration. The Palaeozoic, which includes the oldest 

 fossiliferous beds, the Mesozoic, and the Cainozoic. To these 

 three divisions a fourth of more ancient date may be added, com- 

 prising the Crystalline and Metamorphic rocks, known as Azoic. 

 These are of considerable thickness and are destitute of fossils. 



In comparing the organisation of the Vertebrates with that of 

 inferior forms, we are struck with the complication and diversity 

 of their organs, and how specially they are adapted for their 

 varied modes of life. Compare a man with his complicated 

 brain, and the superiority of his intellectual faculties with all 

 other Vertebrates, how superior the Mammalia are to Birds 

 and these to Reptiles, Batrachians and Fishes in succession, 

 superior too in their organs of respiration, nutrition, and 

 locomotion. In plant-life the Algce, and Fungi, which are very 

 inferior in their organisation to the tree or shrub whose roots, 

 stem, leaves, flowers, and fruit have their special means for 

 fulfilling their role of life. That they appeared in Palaeozoic 

 times is evidenced by fragments of thallus, with bladder-like 

 swellings, found in the tissues of Lepidodendron. There are 

 some groups whose relations to present forms can be determined 

 with more or less certainty. The Diatomaceae, whose siliceous 

 valves occur in the Tertiary and Quaternary deposits, are entirely 

 free from association with any other material, and form layers 

 several feet thick, consisting of a loose white substance, known 

 as Tripoli powder. Ehrenburg, to whom we are indebted for the 

 most searching investigations of fossil Diatoms, shows that many 

 as late as the Cretaceous age belong to living genera, and some 

 are identical with recent species. The Diatom beds appear to 

 have been laid down equally in fresh or salt-water. 



The CharacecB are represented in the Tertiary and Quaternary 

 beds by a considerable number of species, which appear to 

 correspond with recent forms. A number of species are found 

 in the Lower Chalk of the Canton of Neuchatel in Switzerland, 

 and in the Middle Oolites of France. With few exceptions 

 little is known of their palaeontological history. Of the Bryozoa, 



