28 



Tribune Extras Lecture and Letter Series. 



called the Anchithcrium. It had three toes ou each 

 fore foot and three on each hind foot ; but its outer 

 toes were proportionally smaller than those of the 

 Miobippus. The Anchitherium and the Miohippus 

 were about the size of a sheep. 



Alinvc tin- mioeene formation is the pliocene. 

 Again a ires have elapsed while this deposit was form- 

 ing, and here again \ve liave animals of the horse 

 kind. Let us Delect Two of tlieui for exaiuiiiat ion, 

 the llipnarioii and the I'rotohippus. Each has three 

 toes In-fore and three behind, l>ut in no case do the 

 outer toes touch the ground; they are like the pos- 

 terior hooflets of the modern deer and ox. The ser- 

 v in a i ile hoof if e; if!i is atout er t hail in t he preceding 

 animals. 'Hie skull of each has a deep depression, 

 m front of the eye. 



SKULL OF THE IIIPPAKION. 



In the Flioccno we also find the Pliohippus or at 

 least Prof. Marsh does. It has a deep depression 

 under the eye. It and the Ilipparion about equal 

 the ass in Inght. The Pliohippus has but one toe 

 that is, its foot is like the modern horse. 



SKULL, OF THE MODERN HORSE. 



Lastly, at the very top of tho pliocene formation 

 and. just wh'Te it is passing into the quaternary, 

 for the first time tho bones of the true horse are 

 found. It equaled in size the horse of the present 

 day, an 1 in some species surpassed it. The exist inir 

 horse haa DO depression in front of tho orbit. Occa- 

 sionally it has a supcrtluoiis hoof hanging about the 

 true one. 



There are many other facts of a similar character 

 about these skeletons a. id those of other connate 



forme, all indicative of a series, of progression, or 

 as the beln \ i i^ in that theory would call it, of do- 

 \elopment. In respect to the toes the argument 

 maybe briefly stated thus: The single-toed hoof 

 represents the highest capacity for speed; four toes 

 might be useful for support iu the marshes, but tho 



necessity for speed would sooner or later make ani- 

 mals with fewer superllusus toes take precedence 

 of the others. The reduction in the number of toea 

 mav in this manner be due to the gradual elevation 

 and dryintrof the region inhabited. The struggle 

 for existence of the early horse was principally in 

 successfully running away from beasts of prey. 

 Also, the hoof is a weapon of offense. At the present 

 day, if a horse wounded or a mare embarrassed with 

 colt, is overtaken by prairie wolves, the hoof is used 

 to great advantage, each kick that strikes a wolf 

 squarely usually killing it. Nothing could be more 

 inconvenient than superfluous toes in kicking. But 

 what is to be done with the depression in front of 

 the eye? This was developed without apparent 

 reason and disappeared equally without reason. Ah, 

 there are some things, perhaps, which even the de- 

 velopment hypothesis cannot explain. 

 Let us tabulate our facts : 



* The two outer, smaller than those of Miohippns. 



a \ / a 

 \ / \ / 



if W sr 



M XI 1 JK 



MODIFICATION' OF TilK HOOF. 



(1) Forefoot of the Orolnpi.ns. ('-') Foot if tlie .Miohippus. (3) Foot 

 of the Ilipparion. (4) Foot of the modern uorse as occasionally seen, 

 with superfluous hoollrt. 



It will be seen that there are yet more worlds to 

 conquer. Prof. Marsh lives iu the hope of seeing 

 the skeleton of the predecessor of tho Orohippus; 

 say with four toes behind and live in front. And 

 having got that equine ancestor, he will not lie satis- 

 lied till, somewhere at tho bottom of the eocene, or 

 even back in tho cretaceous deposits, he finds the 

 greatest-great-grandfather of all the horses, which 



should be about tho size of a first-class bhu k-and- 

 tan, and should have live well-defined toes on each 

 foot. iouchii.g the ground. With this fossil in his 

 possession. Trot'. Marsh would probably be able to en- 

 joy life without goiugto tho liocky Mountains every 

 Bummer, 



