TEETH OF THE FELIDsE. 



13 



PERMANENT TEETH OF LION. 



i. 3, the third incisor ; c, the canine ; p. I, p. 2, p. 3, the premolars : 

 m, the molars. 



Behind it comes the last of the set, a small 



the lower canines are seen to bite in front of the upper, and to fit into the space between the latter 

 and the incisors. The canines of the Cat are written thus, j=|. 



Following the canines, but separated from them by a slight interval or diastema, are, in the upper 

 jaw four, in the lower three teeth, which correspond to 

 our " grinder-s," or molars and premolars. In the 

 upper jaw the foremost tooth of this set is as small as 

 one of the incisors, and its crown is simple, or nearly 

 so. The next two teeth are larger and have sharp, 

 cutting edges, divided into three points, or cusps. The 

 second of these two teeth is much the larger, its edge 

 is more blade -like, and the front part of its inner edge 

 sends off" a strong blunt process, which is supported by 

 a distinct root, so that this tooth has three roots 

 instead of two like its predecessor ; it is also of much 

 greater size than any of those in front, and, biting like 

 a scissor-blade against the corresponding tooth of the 

 lower jaw, is called the sectorial, or carnassial tooth, 

 tooth with a transversely-set, almost flat crown. 



In the lower jaw, the grinding series is represented by only three teeth, all more or less resem- 

 bling the second of the series in the upper jaw. Of these the third is the largest, and is called the 

 lower carnassial, biting, as it does, against the upper tooth of that name. In every case the teeth of 

 the lower jaw bite within those of the upper, and, the jaws being so articulated as to allow only of up 

 and down motion, and being incapable of play from side to side, the molars and premolars entirely 

 lose their character of grinders, and become trenchant, cutting up the food, in fact, in precisely the 

 same manner as a pair of scissors. 



Now comes the question, which of these teeth are premolars, and which molars ] This is decided 



by finding which of them have their place occupied in 

 the young kitten by its first set of back-teeth, the 

 deciduous or milk molars, and which, on the other hand, 

 have no predecessors : those which replace the milk- 

 molars being the premolars of the adult, those which 

 arise as altogether new teeth, and have no representa- 

 tives in the young animal, molars. The examination of 

 a young Cat shows that there are, behind the canines, 

 in the upper jaw three, and in the lower two teeth ; 

 that is to say, one less on each side of each jaw than 

 in the adult. As age advances these deciduous or milk 

 molars all drop out, and are replaced by the permanent 

 premolars, while behind the last milk molar of each jaw 

 an entirely new tooth makes its appearance the true 

 or permanent molar. Thus it is seen that only the last 

 tooth in each jaw is a molar, and that the carnassials are 

 jrent natures in the two jaws, the upper being the 

 last (third) premolar, the lower the single molar. 

 We therefore write the premolars of the Cat ?=?, and the molars j=|, so that the whole " dental 

 formula " is as follows : i., |=|, c., *=},p., ^, m., ~ = 30. In the milk dentition, the number of incisors 

 and canines is the same as in the adult, and, as we have just stated, the molars are absent, so that the 

 formula is di.,^~, dc., ^~, dm., |^|, = 26, di, dc, dm, standing for deciduous incisors, canines, and molars. 

 The tongue in this family becomes an important adjunct to the teeth, almost losing its character 

 as a delicate organ of taste. The little elevations or papillae which beset the tongue in all animals 

 in ourselves for instance are formed into strong horny spines set closely together like the teeth 

 of a file, and, as may be seen any day at feeding-time at the Zoological Gardens, used to rasp the flesh 

 from the bones as effectively as any file would do it. Most people must have noticed the different 



MILK TEETH OF LIOX, EXPOSED BY CUTTING AWAY 

 THE OUTER PORTIONS OF BOTH JAWS. 



(Natural Size. From (hem, after Rousseau.) 



dJ,decidiiotisIncisors;dc,decidnouscanines;<fn!.l,<Zm.2, dm. 3, n f 

 deciduous molars. The remaining letters have the same signi- OI 

 flcance as in the preceding figure. 



