E. (EUELEPHAS) INDICUS. 151 



the numbers would nearly agree with those comprised in 

 the above formula, 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 diffi- 

 culties ; but it is a question 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 

 should prove to be subject to any great variation in the 

 number of their ridges, the same might reasonably be ex- 

 pected to hold good in the nearly allied 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 hi use 

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

 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 antepe- 

 nultimate 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 different 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. 

 Fiirther, a slight amount of difference in the stage of wear 

 will make an upper antepenultimate present twelve distinct 

 ridges at one time, and only eleven when worn lower down, 

 in consequence of the confluence of the two anterior ridges, 

 exclusive of the talon, into one common disc. Cuvier, in his 

 remarks on the numerical determination of Corse, has ex- 

 pressed his belief that they are not absolute. In proof, he 

 cites a case observed by himself, in which the two consecutive 

 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 anato- 

 mist, 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, 



