His slight, piecemeal glimpse of the animal life of the Paris Basin, and of the few other extinct forms then known, was all he had to depend upon or reason from.

He was not disposed to believe that the thread of life once begun in the earliest times could be arbitrarily broken by catastrophic means; that there was no relation whatever between the earlier and later faunas.

He utterly opposed Cuvier's view that species once formed could ever be lost or become extinct without ancestors or descendants.

He on the contrary believed that species underwent a slow modification, and that the fossil forms are the ancestors of the animals now living.

Moreover, Lamarck was the inventor of the first genealogical tree; his phylogeny, in the second volume of his _Philosophie zoologique_ (p.