On classification and possibilities of a scientific morphology and zoology. CD’s "pedigree business" is important for physiology but has nothing to do with pure zoology any more than human pedigree has to do with the census. Zoological classification is a census of the animal world.

Thinks naturalists look for something further than Cuvier’s view of classification. Poses a theoretical problem on the classification of the races of man to prove that a genealogical system is best.