At the present day, when any student begins to learn the zoology of the lower animals, he will find a very great number of genera with the name of Lamarck placed after them, indicating that he first of all described and published them. As the student becomes accomplished he will appreciate Lamarck more and more, and will come to the conclusion that no one has done such good and solid work as that distinguished Frenchman, amongst the vast assemblage of animals which he first of all called invertebrata, or animals without backbones. This term he used in preference to the old one of white or colourless-blooded animals, as he soon saw that some had red blood. Lamarck worked very hard in describing and grouping the genera, and gradually modified the zoology of those lower forms of life. First of all he classified them by their anatomy, and then, after about fifteen years’ labour, remodelled his classification, and published a system of invertebrata, containing the classes, orders, and genera of the animals, mentioning their most important anatomical characters. In this book he, for the first time amongst zoologists, began with the most simple and least highly organized animals, the converse having been the method previously. There was a reason in this that will be noticed further on. Out of the confusion of old he made the great groups appear clear and well defined. Thus from amongst the insects he separated the crustacea or crab tribe, and he introduced that of the arachnida or spiders. Then he described and limited a class of worms called by him annelida; moreover, he placed the microscopic infusoria in a class by themselves, and removed them from the jumble of the polypes. His work extended into the mollusca, both bivalve and univalve; he named many genera and species of corals, and in every group showed a master mind. The fossil shells found in such abundance at this time, in the neighbourhood of Paris, attracted his attention, and he laboured on their description and explanation. In fact, the enormous labours of Lamarck consolidated the zoology of the lower animals, and his writings became the text-books of all his successors, and will be referred to, as long as science lasts. He had a most singular capacity for distinguishing animals into kinds or species, and a more important one of observing the alliances or common characters of different species. All his descriptive work was of a standard and solid nature. His great work appeared from 1815 to 1822, and it was founded on that just mentioned; some of it was edited by his daughter, and M. Latreille wrote the parts on insects, and much of those of the mollusca was due to M. Valenciennes. Five volumes were by Lamarck himself.