FALCONER MASTODON AND ELEPHANT. 317 



the mean of the various numbers assigned, and making allowance for 

 want of precision in some of the cases in reference to the talons, the 

 numbers would nearly agree wiih those comprised in the above for- 

 mula, which shows a progression by multiples of 4. 



b. True Molars. — The exact determination of the ridge-formula of 

 the true molars is embarrassed by greater difficulties; but it is a ques- 

 tion of considerable importance, more especially as regards the ciphers 

 of the antepenultimate and penultimate, in reference to the confident 

 discrimination of the fossil species. For if, in the living species, these 

 teeth shoiild prove to be subject to any great variation in the number 

 of their ridges, the same might reasonably be expected to hold good 

 in the nearly alhed fossil forms, and a reliance on the ridge-formula 

 as a means of distinction would not be warranted. The causes of 

 the uncertainty are these : — When the animal is adolescent or adult 

 only two at the utmost can be present at one time, on one side of 

 the jaw, out of the six molar teeth developed during life ; and of these 

 two, only one usually is in a perfect state. If the anterior molar is in 

 use and complete, only a part of the posterior tooth is emerged and 

 visible. If the latter is fully protruded, the greater part of the 

 anterior tooth will have been worn away. It is thus impossible 

 ever to trace the details of the dental succession throughout, in any 

 one individual. Then there is a very great difference of size between 

 different animals of the same age. The antepenultimate true molar 

 of a large variety may be nearly as large as the penultimate of a 

 small one. Again, there may be a different estimate of the number 

 of ridges in the same tooth according to the manner in which diffe- 

 rent observers regard the talons. The same last milk-molar may be 

 described by one as having a crown composed of twelve ridges with 

 talons, and by another as having fourteen ridges without them. Fur- 

 ther, a slight amount of difference in the stage of wear will make an 

 upper antepenultimate present twelve. distinct ridges at onetime, 

 and only eleven when worn lower down, in consequence of the con- 

 fluence of the two anterior ridges, exclusive of the talon, into one 

 common disk. Cuvier, in his remarks on the numerical determi- 

 nations of Corse, has expressed his belief that they are not absolute. 

 In proof, he cites a case observed by himself, in which the two con- 

 secutive teeth of a lower jaw presented each fourteen ridges ; while in 

 the corresponding upper jaw the anterior tooth had thirteen ridges in 

 use, and the molar in germ behind it had eighteen ridges. With all 

 deference to the illustrious French anatomist, it may fairly be 

 asked whether in this instance the upper and lower jaws really 

 belonged to the same animal. 



In museums, it is by no means uncommon to see skulls of 

 Elephants fitted with mandibles that do not belong to them, 

 either imported thus from abroad, or having been subjected to 

 some accidental misplacement afterwards. A reliable instance of 

 the kind alleged, as a normal arrangement, has never come 

 under my observation, after the examination of a very large 

 number of skulls in Europe and in India. Inferriag from what 

 is ordinarily seen in the Indian Elephant, the teeth ia the upper 



