And now began a new era in the life of Lamarck.

After twenty-five years spent in botanical research he was compelled, as there seemed nothing else for him to undertake, to assume charge of the collection of invertebrate animals, and to him was assigned that enormous, chaotic mass of forms then known as molluscs, insects, worms, and microscopic animals.

Had he continued to teach botany, we might never have had the Lamarck of biology and biological philosophy.

But turned adrift in a world almost unexplored, he faced the task with his old-time bravery and dogged persistence, and at once showed the skill of a master mind in systematic work.
The two new professorships in zooelogy were filled, one by Lamarck, previously known as a botanist, and the other by the young Etienne Geoffroy St.Hilaire, then twenty-two years old, who was at that time a student of Hauey, and in charge of the minerals, besides teaching mineralogy with especial reference to crystallography.
To Geoffroy was assigned the four classes of vertebrates, but in reality he only occupied himself with the mammals and birds.

Afterwards Lacepede[33] took charge of the reptiles and fishes.