That there has been much inherited variation in the horse cannot be doubted, when we reflect on the number of the breeds existing throughout the world or even within the same country, and when we know that they have largely increased in number since the earliest known records. (2/10. Godron, 'De l'Espece' tome 1 page 378.) Even in so fleeting a character as colour, Hofacker (2/11. 'Ueber die Eigenschaften' etc. 1828 s. 10.) found that, out of 216 cases in which horses of the same colour were paired, only eleven pairs produced foals of a quite different colour. As Professor Low (2/12. 'Domesticated Animals of the British Islands' pages 527, 532. In all the veterinary treatises and papers which I have read, the writers insist in the strongest terms on the inheritance by the horse of all good and bad tendencies and qualities. Perhaps the principle of inheritance is not really stronger in the horse than in any other animal; but, from its value, the tendency has been more carefully observed.) has remarked, the English race-horse offers the best possible evidence of inheritance. The pedigree of a race-horse is of more value in judging of its probable success than its appearance: "King Herod" gained in prizes 201,505 pounds sterling, and begot 497 winners; "Eclipse" begot 334 winners. Whether the whole amount of difference between the various breeds has arisen under domestication is doubtful. From the fertility of the most distinct breeds (2/13. Andrew Knight crossed breeds so different in size as a dray-horse and Norwegian pony: see A. Walker on 'Intermarriage' 1838 page 205.) when crossed, naturalists have generally looked at all the breeds as having descended from a single species. Few will agree with Colonel H. Smith, who believes that they have descended from no less than five primitive and differently coloured stocks. (2/14. 'Nat. Library, Horses' volume 12 page 208.) But as several species and varieties of the horse existed (2/15. Gervais 'Hist. Nat. Mamm.' tome 2 page 143. Owen 'British Fossil Mammals' page 383.) during the later tertiary periods, and as Rutimeyer found differences in the size and form of the skull in the earliest known domesticated horses (2/16. 'Kenntniss der fossilen Pferde' 1863 s. 131.), we ought not to feel sure that all our breeds are descended from a single species. The savages of North and South America easily reclaim the feral horses, so that there is no improbability in savages in various quarters of the world having domesticated more than one native species or natural race. M. Sanson (2/17. 'Comptes rendus' 1866 page 485 and 'Journal de l'Anat. et de la Phys.' Mai 1868.) thinks that he has proved that two distinct species have been domesticated, one in the East, and one in North Africa; and that these differed in the number of their lumbar vertebra and in various other parts; but M. Sanson seems to believe that osteological characters are subject to very little variation, which is certainly a mistake.