Fleischmann devotes a long chapter to the geological evidences in connection with the evolution of the horse, and attempts to throw ridicule on the conclusions of the paleontologists by emphasizing the differences of opinion that have been advanced in regard to the descent of this form. After pointing out that the horse, and its few living relatives, the ass and the zebra, are unique in the mammalian series in possessing a single digit, he shows that by the discovery of the fossil horses the group has been simply enlarged, and now includes horses with one, three, and five toes. The discovery of the fossil forms was interpreted by the advocates of the descent theory as a demonstration of the theory. The series was arranged by paleontologists so that the five-toed form came first, then those with three and one toe, the last represented by the living horses. But the matter was not so simple, Fleischmann points out, as it appeared to be to the earlier writers, for example to Haeckel, Huxley, Leidy, Cope, Marsh. Different authors came to express different opinions in regard to the genealogical connection between the fossil forms. Several writers have tried to show that the present genus, Equus, has not had a single line of descent, but have supposed that the European horses and the original American horses had different lines of ancestry, which may have united only far back in the genus Epihippus. Fleischmann points out that the arrangement of the series is open to the criticism that it is arbitrary, and that we could equally well make up an analogous series beginning with the five-fingered hand of man, then that of the dog with the thumb incompletely developed, then the four-fingered hind-foot of the pig without a big toe and with a weak second and fifth digit, then the foot of the camel with only two toes, and lastly the foot of the horse with only one toe. It sounds strange that Fleischmann should make such a trivial reply as this, and deliberately ignore the all-important evidence with which he is, of course, as is every zoologist, perfectly conversant. Not only are there a hundred other points of agreement in the horse series, but also the geological sequence of the strata, in which some at least of the series have been found, shows that the arrangement is not arbitrary, as he implies.