THE biological aspect of palaeontology forms the topic of Prof. H. L. Hawkins's presidential address to Section C (Geology). The first part of the address is a re-statement of-the basic facts about fossils, and is followed by an appraisement of their value in the attempt to decipher the history of life. Comparison of the records of palseontology and human history shows that fossils, for all their incompleteness, give on the whole a surer basis for historical reconstruction than documents or monuments. A corresponding comparison between the principles of taxonomy in palaeontology and neontology shows inevitable differences that may lead to confusion if overlooked. Many of the characters of living organisms, rightly regarded as of specific value by neonto-logists, are quite inaccessible in fossil material; even when they seem to be recognizable, they cannot be proved to have a truly specific significance. In skeletal structures, differences that would justify taxonomic distinction between fossils can usually be matched with generic or even family differences in living organisms. Hence such terms as ‘genus’ or ‘species’ are used in different senses, and should be enclosed in inverted commas when applied to fossils.