Cockerell states that he finds Chapman's zebra a very good species to use for the process of measuring skulls. He details at length the various measurements of skulls from the different Equus species, and encloses remarks made by James W. Gidley on this subject.

Cockerell writes regarding the notes that he had sent about Equus scotti, and the apparent differences between this species and Equus caballus, an opinion he has now had to alter in the light of information supplied by James Gidley. Cockerell doubts whether the bones of any species of horse would indicate from which hemisphere it originated.