402 HISTORY OF SCIENCE. 



series of memoirs on Mollusca ; then his great work on Fossil Bones ; 

 and in 1817 "The Animal Kingdom," in which he attempted to ar- 

 range all known animals according to their natural affinities as deduced 

 from a comparative view of the whole organizations. Buffon in his 

 "Histoire Naturelle" had been contented to follow Pliny, by taking 

 merely the external appearance as the basis of his system. Cuvier 

 improved systematic zoology by making the differences of organiza- 

 tion revealed by comparative anatomy his guide. Cuvier divided the 

 animal kingdom into four sub-kingdoms viz., the Vertebrata, the 

 Mollusca, the Annulosa, the Radiata because these respectively ex- 

 hibited four great fundamental types on which all animals appear to 

 have been modelled, and of which all their forms may be regarded as 



FIG. 184. SKELETON OF MYLODON ROBUSTUM (an extinct vertebrate). 



comparatively slight modifications, in which certain organs are more 

 or less developed in various directions while the general organization 

 of the typical form is adhered to. He rejected Lamarck's twofold 

 division into Vertebrate and Invertebrate, on the ground that there was 

 between the subdivisions of the last as great a difference of structure 

 as between the two divisions themselves. 



The latest work undertaken by Cuvier was an admirable description 

 of the geology of the environs of Paris, and in the composition of this 

 work he had for coadjutor ALEXANDER BRONGNIART (1770 1847), 

 who was Professor of Natural History and of Mineralogy at Paris. 

 Brongniart began life as an officer in the army, but after he had shown 

 liis ability in natural science, he was in 1800 appointed Director of the 

 Sevres Porcelain Manufactory, where his scientific acquirements proved 

 of high value. It was he who first "divided the Reptilia into Saurians, 

 JBatrachians, Chelonians, and Ophidians. 



HALLER (1708 1777) was one of the most indefatigable anato- 



