CHAP. II. DENTITION OF FARM ANIMALS. 415 



From the foregoing it will be understood that the ox and the sheep 

 have no incisor teeth in the upper jaw, the faces of the premaxillary 

 bones being covered instead with a thick cartilaginous pad against 

 which the incisors in th( lower jaw can bite. In the " full mouth " of 

 the ox and sheep there are, as in the case of the horse (see Table on 

 next page), six molars above and below, on each side, the front three 

 of which have had predecessors. Sometimes, too, the insignificant 

 little "wolf" tooth, which may occasionally be seen on the near side 

 of the first of the six molars of the horse, is noticeable in the milk 

 dentition of ruminants. An interesting question suggests itself as to 

 why the horse should have only three incisors on each side of the 

 middle line, above and below, and the ox and sheep should have 

 four incisors on each side of the middle line of the lower jaw. The 

 theory is that the fourth incisor on each side, or the " corner " 

 incisor, is really a canine tooth, and, therefore, equivalent to the 

 "tush" in a horse; but whereas in the horse there is a space 

 between the tushes and the compact row of incisors (in the mare the 

 tushes are usually absent), in oxen and sheep there is none. In his 

 treatise, "A Manual of the Anatomy of Vertebrated Animals," Professor 

 Huxley says of the Ruminantia, or animals that chew the cud : 

 "Canines mayor may not exist in the upper jaw; they are always 

 present in the lower jaw, and are generally inclined forwards and closely 

 approximated to the incisors, which they usually resemble in form. It 

 consequently happens that they are often reckoned as incisors, and 

 Ruminants are said to possess eight cutting teeth in the lower jaw." 

 In cattle and sheep, as in horses, there is a considerable space between 

 the incisors and the molars. In the horse this space is called the 

 "bar," and it affords room for the bit. 



The subjoined diagram shows the relative positions of the incisors of 

 the ox and sheep, and the nomenclature which follows will be readily 

 understood. 



DIAGRAM SHOWING POSITION OF INCISOR TEETH IN LOWER JAW OF CATTLE 



AND SHEEP. 



Middle 

 of jaw. 



1 1, 2 2, 3 3, 4 4, are the incisors. 



1 1 are the central permanent incisors, or the centrals or pincers. 



2 2 are the second pair of incisors, or the first intermediates or 

 middles. 



3 3 are the third pair of incisors, or the second intermediates or 

 laterals. 



4 4 are the fourth pair of incisors, or corners. 



Sheep are named according to the stage of replacement of the incisor 

 teeth. When the permanent centrals (1, 1) appear the animal is a 

 " two-teeth " sheep ; when the permanent middles (2, 2) appear it is a 



