62 THE HORSE. 



divisions of it, vertehrce, proceeding from the cranium, and containing a 

 prolongation of the brain, denominated the spbial marrow. 



Invertebrated animals are those which have no vertebrae. 



The horse then belongs to the division vertebrated, because he has a 

 cranium or skull, and a spine or range of vertebrae proceeding from it. 



The vertebrated animals, however, are very numerous. They include 

 man, quadrupeds of all kinds, birds, fishes, and many reptiles. We look 

 out then for some subdivision, and a very simple line of distinction is soon 

 presented. Some of these vertebrated animals have mamm(B or teats, with 

 which the females suckle their young. The human female has two, the 

 mare has two, the cow four, the bitch ten or twelve, and the sow more than 

 twelve. 



This class of vertebrated animals, having mammae or teats, is called 

 mammcdia, and the horse belongs to the division vertebratay and the class 

 mammalia. 



The class mammalia is still exceedingly large, and we must again sub- 

 divide it. It is stated (Library of Entertaining Knowledge, vol. i. p. 13) 

 that " this class of quadrupeds, or mammiferous quadrupeds, admits of a 

 division into two Tribes. 



" I. Those whose extremities are divided into fingers or toes, scientifi- 

 cally called unguiculata, from the Latin word for nail ; and II. Those 

 whose extremities are hoofed, scientifically called uiigulata, from the Latin 

 word for hoof. 



" The extremities of the first are armed with claws or nails, which 

 enable them to grasp, to climb, or to burrow. The extremities of the 

 second tribe are employed merely to support and move the body." 



The extremities of the horse are covered with a hoof, by which the body 

 is supported, and with which he cannot grasp anything, and therefore he 

 belongs to the tribe ungulata, or hoofed. 



But there is a great variety of hoofed animals. The elephant, the 

 rhinoceros, the hippopotamus, the swine, the horse, the sheep, the deer, 

 and many others, are ungulated or hoofed ; they admit, however, of an 

 easy division. Some of them masticate, or chew their food, and it is im- 

 mediately received into the stomach and digested ; but in others, the food, 

 previous to digestion, imdergoes a very singular process. It is returned 

 to the mouth to be re-masticated, or chewed again. These are called rumi- 

 nantia, or ruminants, from the food being returned, from one of the 

 stomachs (for they have four) called the rumen or paunch, to be chewed 

 again. 



The ungxdata that do not ruminate are somewhat improperly called 

 pachydermata, from the thickness of their skins. The horse does not 

 ruminate, and therefore belongs to the order pachydermata. 



The pachydermata who have only one toe belong to the family solipeda 

 — single footed. Therefore the horse ranks under the division vertebrata ; 

 the class mammalia; — the tribe ungulata; — the order pachydermata; — 

 and the family solipeda. 



The solipeda consists of several species, as the horse, the ass, the mule, 

 and the qua2:ga. 



First stands the Equus Caballus, or Common Horse. 



Animals are likewise distinguished according to the number, description, 

 and situation of their teeth. The horse has 6 incisors or cutting teeth, in 

 the front of each jaw ; and one canine tooth or tusk. 



On each side, above and below, and at some distance from the incisors, 

 behind the canines and with some intervening space, are six molar teeth, 



