RUMINANTS. 



)27 



commune is i^^fii of an inch : that of their interspaces, in the 

 middle of the dentine is g^th of an inch. The diameter of the 

 sub-hexagonal dentinal cells is ^^th of an inch. The purkingian 

 cells of the cement are for the most part oblong, 4jjjoth of an 

 inch in largest diameter. 



The vast abundance of Anoplotherian remains accumulated in 

 the ancient lacustrine deposits which now form the gypsum-quarries 

 at Montmartre, afforded Cuvier evidence not only of the changes 

 produced in the form of the teeth by mastication, but also by 

 the shedding and succession of the teeth. The deciduous formula 

 of the Anoplotherium is : — 



Incisors — : canines — ; molars — : = 32. 



3-3 ' 1-1 ' 4—4 



The incisors and canines w^ere replaced by teeth of similar form, 

 but of larger size : the deciduous molars by teeth of more simple 

 conformation ; the deciduous molars typifying the structure of the 

 permanent true molars, but the last in the lower jaw having the 

 third posterior lobe of larger proportional size than in the last lower 

 true molar. We cannot but recognize with much interest the 

 constancy in the number of the true molar teeth under all their 

 diversified forms in the existing Ungulata not proboscidian ; but 

 that interest is greatly heightened when we find that the 

 same law both as regards the number of true molars, and the 

 inferior complexity of the premolars to the deciduous teeth which 

 they displace, has prevailed from the remote period when we first 

 obtain evidence of hoofed Herbivora on the surface of this planet. 



192. Ruminantia. — ^The essential character of the dentition of 

 all Mammalia, which by the Ungulate modification of their loco- 

 motive extremities are deprived of one of the means of seizing a 

 living prey, is the complex structure of the molar teeth, produced 

 by an interblending of the dental tissues in the crown, whereby 

 they are made more efiicient instruments for the mastication of 

 vegetable substances. 



Different groups of Ungulata, not only Orders and Genera but 

 even species, are characterised by the various patterns which result 

 from the various forms, directions and proportions in which the 



