PACIIYDERMATA. 



latter there is never more than one wholly, or 

 two partially in place and use on each side at 

 any given time ; for like the molars of the 

 Mastodons, the series is continually in progress 

 of formation and destruction, of shedding and 

 replacement, and in the Elephants all the 

 grinders succeed one another horizontally, from 

 behind forwards, none being displaced and 

 replaced by vertical successors or premolars. 



The total number of teeth developed in the 

 Elephant Professor Owen believes to be 



2.2 6.6 



Incis. - Molars - = 28, 



0.0 6.6 



the two large permanent tusks being preceded 

 by two small deciduous ones, and the number 

 of molar teeth which follow each other being 

 at least six ; but Mons. Corse was of opinion 

 that this replacement of teeth is repeated at 

 least eight times in the Indian Elephant, which 

 would consequently have thirty-two teeth suc- 

 cessively taking their respective places in the 

 jaws. 



The deciduous tusk makes its appearance 

 beyond the gum between the fifth and seventh 

 month ; it rarely exceeds two inches in length, 

 and is about a third of an inch in diame- 

 ter at its thickest part, where it protrudes 

 from the socket; the fang is solidified, and 

 contracts to its termination, which is commonly 

 a little bent and is considerably absorbed by 

 the time the tooth is shed, which takes place 

 between the first and second year. 



The socket of the permanent tusk in a new- 

 born Elephant is a round cell about three lines 

 in diameter, situated on the inner and posterior 

 side of the aperture of the temporary socket. 

 The permanent tusks cut the gum when about 

 an inch in length, a month or two usually after 

 the milk teeth are shed. The widely-open 

 base of the tusk is fixed upon a conical pulp, 

 which, with the capsule surrounding the base, 

 progressively increases in size, stimulates a 

 concomitant increase in the capacity and depth 

 of the socket, which cavity soon obliterates 

 that of the deciduous tusk. 



These incisive teeth of the Elephant not 

 only surpass other teeth in size, as belonging 

 to a quadruped so enormous, but they are the 

 largest of all teeth in proportion to the size of 

 the body, representing in a natural state those 

 monstrous incisors of Rodents which are the 

 result of accidental suppression of the wearing 

 force of the opposite teeth. 



The molar teeth of the Elephant are remark- 

 able for their great size, even in relation to the 

 bulk of the animal, and for the extreme com- 

 plexity of their structure. The crown, of which 

 a great propoition is buried in the socket, and 

 very little more than the grinding surface ap- 

 pears above the gum, is deeply divided into a 

 number of transverse perpendicular plates, 

 consisting each of a body of dentine, coated 

 by a layer of enamel, and this by a less dense 

 bone-like substance which fills the interspaces 

 of the enamelled plates, and here more espe- 

 cially merits the name of cement, since it binds 

 together the several divisions of the tooth 

 before they are fully formed and united by the 



confluence of their bases into a common body 

 of dentine. 



The manner in which these complex teetli 

 are formed is a subject of great interest, and 

 has been ably investigated by many celebrated 

 anatomists, particularly by the two Campers, 

 father and son, M. Corse, Robert Blake, and 

 John Hunter, whose splendid preparations illus- 

 trative of the process are contained in the 

 Museum of the Royal College of Surgeons in 

 London. It is to Cuvier, however, we are 

 indebted for the most complete and lumi- 

 nous exposition of this important piece of 

 physiology, as may be gathered from the fol- 

 lowing account extracted from his great work, 

 " Recherches sur les Ossemens Fossiles." 

 " The molar tooth of the Elephant, like every 

 other mammiferous tooth, is formed in the in- 

 terior of a membranous sac, now generally 

 called the capsule of the tooth. This capsule 

 has in the Elephant a rhomboidal form, and is 

 closed on all sides, excepting the small open- 

 ings for the passage of nerves and vessels. It 

 is lodged in a bony cavity of the same shape 

 as itself, excavated in the maxillary bone, which 

 afterwards forms the socket of the tooth." 



" It is, however, only the external lamina of 

 the capsule which is thus simple in its arrange- 

 ment, the inner lamina being, as in all other 

 herbivorous animals, thrown into numerous 

 folds, as will be understood when we have 

 described the pulp upon which the tooth is 

 formed." 



" This pulp has in every animal its peculiar 

 arrangement. To represent that of the Ele- 

 phant, we must imagine that from the bottom 

 of the capsule as from a base, there arise nu- 

 merous parallel and transverse walls which 

 mount upwards towards that part of the cap- 

 sule which is placed next to the gums. These 

 little walls are only adherent to the floor of the 

 capsule, their opposite extremity or summit 

 being free from all adherence." 



" The free summit is much thinner than the 

 base, so that it might be called the edge, and 

 is moreover deeply cleft in many parts, so as to 

 form numerous sharp points and indentations. 

 The substance of these little walls is soft, trans- 

 parent, and very vascular, containing appa- 

 rently much gelatine : it becomes hard, white, 

 and opaque in spirits of wine." 



" It will be now easy to understand the 

 manner in which the inner membrane of the 

 capsule is folded, if we imagine it to form pro- 

 longations which penetrate into all the intervals 

 between the little walls above described. These 

 prolongations adhere to the upper part of the 

 capsule, that is, to the side of it which is nearest 

 the gums, and also to its lateral parietes, but 

 are not adherent to its base, from whence the 

 little gelatinous walls above described arise. 

 Consequently it is easy to understand that there 

 may be a continuous cavity amazingly folded 

 upon itself, extending between all the gelati- 

 nous walls (which are descending in the upper 

 teeth, ascending in the lower teeth) and these 

 membranous partitions (ascending in the upper 

 teeth, descending in the lower teeth.)" 



" It is in this conceivable cavity that the ma- 



