KI.KI'HANT. 



ELEPHANT. 



MM 



African Elephant : Incuora, 2 ; Molar*,* . 10. 



Asiatic Elephant : Inciaora, - ; Molar*, - . 



TVntitlon n<l O**eont Structure. The meoion of moUr teeth in 

 U> elephant* take* place in a direction from behind forward* ; and 

 the tooth but developed pushing apunrt that which preceded it, and 

 in time replacing it. give* a* a rwult that there are never more than 

 two molar teeth on each aid* of each jaw, and t Imt sometime* there U 

 only one. The la*t case happen* immediately after the shedding of 

 the anterior tooth, which ha* been pushed out by it* successor, and 

 which, in iu torn, U to be replaced in like manner. Thi* succession 

 happen* many time* during the life of the animal, and Mr. Corse 

 noticed it eicht time* in an Asiatic Elephant. Now, a* theae teeth 

 bow their anterior extremity first, long before the other extremity 

 appear*, and a* they begin to be worn down anteriorly, it follows that 

 the anterior tooth, when it is abed, is infinitely smaller in size than it 

 once waa, and that it* form i* entirely changed. 



In the molar teeth of most graminivorous quadrupeds there is, 

 betide* the bony substance and enamel, a third component part, 

 differing in appearance from both the others, but resembling the bone 

 more than the enamel. Blake and others have distinguished tliis 

 ubetance by the name of 'cnista petroea;' Cuvier calls it 'cement' 

 The distinction of tbeae three substances is perhaps better seen in 

 the molar tooth of an elephant than in any other animal If a longi- 

 tudinal vertical section be made and the surface be polished, the 

 crusta petroaa will be distinguished by a greater yellowness and 

 opacity, a* well u by a uniformity of appearance, there being no 

 rpparent laminrc nor fibres. "The grinding troth of the elephant," 

 write* Lawrence in hi* 'Additions' to Blumenbach, "contain the 

 moat complete intermixture of there three substances, and have a 

 greater proportion of crusta petrosa than those of any other animal. 

 The pulp forms a number of broad flat processes lying parallel to 

 each other, and placed transversely between the inner and outer 

 lamina* of the alveoli. The bone of the tooth is formed on these in 

 separate shell*, commencing at their loose extremities and extending 

 toward* the basin, where they are connected together. The capsule 

 end* an equal number of membranous productions, which first cover 

 the bony ahell* with enamel and then invest them with crusta petrosa, 

 which latter substance unites and consolidates the different portions. 

 The bony shells vary in number from 4 to 23, according to the size 

 of the tooth and the age of the animal ; they have been described under 

 the name of denticuli, and hare been represented as separate teeth in 

 the first instance. It must however be remembered that they are 

 formed on processes of one single pulp. When the crusta petrosa is 

 completely deposited, the different denticuli are consolidated together. 

 The bony shell* are united at the base to the neighbouring ones ; the 

 investment* of enamel are joined in like manner ; and the intervals 

 are filled with the third substance, which really deserves the name 

 bestowed on it by Cuvier of ' cement' The pulp is then elongated 

 for the purpose of forming the roots or fangs of the tooth. From the 

 peculiar mode of dentition of this animal, the front portion of the 

 tooth has cut the gum and is employed in mastication before the back 

 part is completely formed ; even be/ore some of the posterior denti- 

 culi hare been consolidated. The back of the tooth does not appear in 

 the mouth until the anterior part has been worn down even to the 

 fang. A horizontal section of the elephant's tooth presents a aeries 

 of narrow band* of bone of the tooth, surrounded by corresponding 

 portions of enamel Between these are portions of crusta petrosa ; 

 and the whole circumference of the section is composed of a thick 

 layer of the same substance. A vertical section in the longitudinal 

 direction exhibit* the proceese* of bone upon the different deiiticuli, 

 running up from the fang* ; a vertical layer of enamel is placed before 

 and another behind each of the*e. If the tooth is not yet worn by 

 maetication, the two layer* of enamel are continuous at the part 

 where the boo* terminate* in a point ; and the front layer of one 

 denticaln* U continuous with the back layer of the succeeding one 

 at the root of the tooth. Cruata petroaa intervene* between the 

 aacending and descending portion* of the enamel A* the rarface of 

 tbetooth i* worn down in martication, the processes of enamel, 

 reefatin*; ">7 *>* superior hardneat, form prominent ridge* on the 

 grinding *urt*oe, which must adapt it excellently for bruiaing and 

 comminuting any hard subrtance. The grinding bane*, when worn 

 ocfratly to expoae the enamel, in the Asiatic species, represent 

 flattened oral* placed aeros* the tooth. In the African they form a 

 sriei of loMogea, which touch each other iu the middle of the tooth." 

 In the Muaeum of the Royal College of Surgeon* are a aerie* of pre- 

 paration* (No*. 850 to 854, both inclusive) illustrative of the tructure 

 andphTaiology of the molar teeth of elephant*, preceded by an 

 jnterating extract from the Hunterian MS. Catalogue. No. 275 B 

 to a portion of the cnmentom of an elephant'* grinder, which ha* been 

 leeped in an acid, dried, and preferred in oil of turpentine, for the 

 of *bowing the proportion of animal matter which it contains. 

 2 to 284, both inclusive, show the interarticular ligamentou* 

 from the joint of the lower jaw of the elephant, and the 

 MOO of the structure for applying two convex surfaces to each 



Teeth of African Elephant. From F. Cuvier. 



a, I'ppcr jaw ; 4, lower Jaw ; e, original state of the tooth when the lamina) 

 which compote it arc free ; d, the lamina? as they ore attached in parallel" on* 

 to the other by the cortical subRtnnce in a subsequent state of dentition, but 

 before the crown of the tooth has been worn by implication, and when it only 

 present* on IU surface blunt tubercles. 



Tefi of Asiatic Elephant > mm F. Cuvier. 

 a, U;ipcr molar tooth ; 6, lower molar tooth. 



