1 76 FROM LAMARCK TO ST. HILAIRE. 



early as 1802 he held that affinities indicate com- 

 munity of parentage, and that it is necessary to 

 prove that the series which constitutes the animal 

 scale resides essentially in the distribution of the 

 principal masses which compose it, and not in that 

 of the species, nor even of the genera. As we see 

 in the above tables, Lamarck's attempts at recon- 

 structing the tree of life were crude, but consider- 

 ing the infancy of Paleontology and the entire 

 absence of embryological knowledge, his specula- 

 tions appear more to his credit. He supposed that 

 mammals passed through amphibious mammals back 

 to saurians similar to crocodiles. The seals or 

 aquatic mammalia gave rise to the Unguiculates or 

 clawed animals, and when the claws became too 

 long, the Carnivores made efforts to retract them. 

 Some primitive mammals did not leave the water 

 at all, but lost their limbs and became the Cetacea. 

 It is strange that Lamarck grasped the true idea 

 of extinction of the lower types, but not of the higher 

 types. He could not credit the extinction of such 

 perfect forms as the Mastodon or the Paleotherium 

 by any of the forces of Nature, but believed that 

 they had probably been exterminated by man, or 

 that these species might still be found alive else- 

 where. He thoroughly believed in the extinction 

 of lower types, for example, of the Molluscs, and 

 that the lower types had given way to the higher, 

 the ranks of the lower types being constantly replen- 

 ished by incessant creation of the lowest forms. 



