E L E : 
begin to cut the gum.' From tlie end of'the fecond to 
the beginning of the lixth year, the third fet come gra¬ 
dually forward, as the jaw lengthens, not only to fill up 
this additional fpace, but all’o t,o fivpply the place of the 
fecond fet, which are, during the fame period, gradually 
worn away, and their fangs abforbed.- From the begin¬ 
ning of the lixth to the end of the ninth year, the fourth 
fet of grinders corite forward, to fupply the gradual wade 
of the third fet. After this period, feveral other-lets are 
produced. In what time thefe fucceeding grinders come 
forward, in proportion to their predeceffors, I have not 
been able to afcertain ; but, from the data already given, 
I conclude, that every fucceeding grinder takes at lead a 
year more than its predcceffor to be completed; confe- 
quently, that the fifth, fixth, feventh, and eighth, fet of 
grinders, (a further fuccedion I have not been able to 
trace,) will take from five to eight years (and probably 
much longer) each fet, before the poderior lamina has 
cut the gum. All thefe circumdances conddered, I may 
venture to affirm, that the formation of the teeth and 
mode of dentition, in the elephant, has but little analogy 
with thofe of any other quadruped ; nature having, by 
a peculiar and. wonderful contrivance, and in the mod 
convenient manner, fupplied this animal with a regular 
fuccedion of teeth, until he attains a very advanced pe¬ 
riod of life. 
“ The mode in which the elephant’s grinders are ori¬ 
ginally-formed, my Ihort day at Tipeiah did not allow 
me fuffieient opportunities to invedigate ; but, fmce my 
return to England, I have had frequent converfations 
with Mr. Everard Horne, F.R.S. upon that fubjeCt, 
who, from an examination of the teeth brought home 
by me, and fome preparations in the late Mr. Hunter’s 
collection, has been enabled to profecute the fubjeCt 
with condderable fuccefs.” 
The objeCt of this gentleman was not only to explain 
the druCture of the elephant’s teeth, and hence the dif¬ 
ferent lources and didinCtions between ivory and bone ; but 
alfo to diew the general principle upon w'hich all teeth 
are formed, that have the enamel intermixed with the 
fubdance of the teeth ; a fubjeCt which appears never 
before to have been invedigated. 
“The teeth of the elephant (fays Mr. Home) differ 
from others, in being compofed of a great many flattened 
oval procelfes ; thefe, while growing, are detached ; but, 
when completely formed, their bafes unite together, and 
make the body of the tooth, to which the fangs are af¬ 
terwards added ; .and, as the fangs are lengthened, the 
tooth rifes in the jaw. This is what may be conddered 
as the tooth itfelf, being compofed of the fame materials 
as the teeth of carnivorous animals ; but, in addition, 
there is another fubdance, which unites all the procelfes 
together, laterally, into one mafs ; this is fofterthan the 
fubdance of the tooth, and, upon examination, proves to 
be dmilar, in its texture and formation, to common bone. 
As teeth have been hitherto conddered of the fame tex¬ 
ture with common bone; it is probable that nothing but 
the two fubdances being united in the fame mafs, could 
have led me to the difcovery of their differing materially 
from each other. It will therefore be proper to explain 
the circumdances which fird gave me the prefent view of 
the fubjeCt. 
“To obtain an accurate knowledge of the different 
parts of the elephant’s tooth, a longitudinal feCtion was 
made, of one that was full grown. This feCtion expofed 
the lateral connection between the different proceffes, and 
the intermediate fubdance which unites them into one 
mafs ; it alfo (hewed the mode in which the proceffes are 
continued into the body of the tooth and fangs. That 
the internal druCture might be made more diltinCt, the 
furface of this feCtion was polifhed very highly, which 
led to the difcovery of the proceffes of the tooth having 
a more compaCt texture than the intermediate fubdance ; 
for, although both had the fame appearance after being 
fawn, the proceffes bore a polifli, which the other did not, 
Vol. VI. No. 364.. : 
' H A S. '46a 
and were laminated, like ivory; while the other parts 
were porous, like the internal druCture of common bone. 
This led me to. examine preparations of the elephant's 
teeth, in a growing date, preferved in fpirit, which ex¬ 
plained the mode of growth of thefe two fp.bjfances to 
be different. In thefe preparations it was found, that 
the proceffes of the tooth, which may be called ivory, 
were all formed upon fo many portions of one common 
pulp, which had its origin in the jaw; and that the in¬ 
termediate fubdance, which may be called bone, was 
formed upon a fpeCies of ligament fituated immediately 
under the gum, from which, membranous elongations ex¬ 
tended into the fpaces between the procelfes of the tooth, 
“ This druCture of tooth is not peculiar to the ele¬ 
phant, but common to the teeth of all animals whole, 
food requires to be ground, or much bruifed, before it is 
lwallowed. In the elephant’s tooth, from the largenefs 
of its fize, the parts are‘more didinCt, and more readily 
confraded with each other ; but, in other animals, even 
thofe of a final 1 fize, as the fheep, the diflerent druClures 
are readily detected. It is fingular that this druCture 
dlould have efcaped the accurate invedigation of the late 
Mr. Hunter; particularly as the formation of the teeth 
was one of the fird objects.he employed himfelf upon ; 
and he continued to purfue it to the end of his life, 
marking the varieties which occur in different •animals. 
. “ A mixture of bony matter with the enamel and the 
fubdance of the tooth, is a druCture, as has been men¬ 
tioned, not confined to the elephant, being common to all 
truly graminivorous, quadrupeds. But the whole num¬ 
ber of grinding teeth belonging to each fide of the jaw 
being confined in a cafe of bone, fo as to form one large 
grinding furface, and the teeth being pufiied torwaid 
from behind, indead of a fecond fet being formed imme. 
diately under the fangs of the fird, as in other animals, 
are peculiarities not met with in any teeth hitherto de- 
feribed, except thofe of the elepharif, and the_/i« jEthio- 
picus. It is curious that the Ethiopian hog fltould djifer 
fo widely from all the others.of its genus, in refpeCt to 
its teeth ; and Oiould be allied to the elephant in the 
druCture of its tufks, the mode of formation of the grind¬ 
ing teeth, and the manner in which they fucceed one ano¬ 
ther. From thefe circumdances it appears, that the Jus 
/Ethiopicus, in a natural date, is fupplied with a different 
kind of food from that of other hogs, and is an animal 
of greater longevity.” 
This fingular mode of dentition has not been noticed, 
by profeffor Camper, in bis ingenious work above-men¬ 
tioned ; but he has fhewn that the druCture of the cra¬ 
nium is admirably adapted to afford a fuffieient extent of 
furface for the infertion of the tufks, the probofeis, and 
mufcles, without unneceffarily i’ncfeafing its weight; for 
otherwise the animal would never have.been able to carry 
its head ereCt. We filial 1 give a tranflation of the ac¬ 
count of this piece of mechanifm as follows : “ In order 
to include the encephalon within proper bounds, and to 
allow a fuffieient fpace for the infertion of the tufks, pro¬ 
bofeis, and mufcles, without loading the head with a 
weight of offeous matter, the tables are feparated from 
each other by a great number of bony partitions, pro¬ 
longed to the didance of feveral inches. The intervals, 
filled by an infinity of little cells more or lefs fpacious, 
communicate with the throat by means of the eudachian 
tube, and are charged with air, indead of blood or mar¬ 
row, which are generally found in the diploe of the mam¬ 
malia clafs. Perrault, Blair, and Daubenton, have re¬ 
marked this druCture in the elephant, boar, and other 
quadrupeds: but M. Camper was the fird to notice its 
analogy with the druCture of the cranium in birds. The 
odrich and the eagle, but above all the owl tribe, parti¬ 
cularly the fcreech-owi, have the tables of the fleu 11 fe¬ 
parated by numerous cells, perfectly dmilar to thofe 
which didinguifh the elephant. The atmofpheric air 
enters them in the fame way ; and this admirable mecha- 
nifm, which birds particularly require to diminiffi the 
6 C weight 
