346 PROGRESS OF SCIENCE IN THE CENTURY. 



of fossil remains often demands, e.g., in the case of 

 fishes, a prolonged special training. " The nature 

 of the remains with which the palaeontologist has 

 to deal renders their interpretation a task of so 

 different a character from that allotted to the in- 

 vestigation of the structure and development of 

 recent forms " * that the necessary division of labour 

 tends to be exaggerated. Of the founders of palae- 

 ontology three were on the whole biological, — Cuvier 

 (Tertiary mammals), Lamarck (Molluscs), and 

 Brongniart (Plants), while William Smith was 

 mainly interested in the relation of the fossils to 

 stratigraphical problems. 



The palaeontological work of the nineteenth century 

 has been marked by several different kinds of achieve- 

 ments: — the compilation of a descriptive census of 

 the extinct, the anatomical study of lost races, 

 i.e., of those with no living representatives, nor, so 

 far as we know, direct descendants, the discovery of 

 missing links, and the working out of pedigree-lines 

 in particular groups. 



Study of Lost Races. — In studying fossils a dis- 

 tinction must be drawn between {a) those which 

 are in no sense extinct, being represented to-day by 

 living forms, e.g., Lingula, Estheria, Ceratodus, (b) 

 those which, though forming extinct species, are 

 represented to-day by living descendants, as is true 

 of a very large number, and (c) those which are 

 without known living descendants, which we must 

 therefore call extinct types or lost races, e.g., Grap- 

 tolites and Trilobites, Eurypterids and Pterodactyls. 

 It is indeed a distinction of degrees, and more de- 

 grees might be recognised, but it is plain that the 



♦Traquair, Joe. cit. 



