~ 1807.) 
in the upper jaw have three. The first 
of the former are thinner, and crooked 
from before backwards; those of the 
latter were crooked towards the palate, 
This curvature distinguishes them from 
the front grinders, whether they be milk- 
teeth, or those ‘succeeding them, which 
are always straight. 
The former of these back grinders are 
visible in the alveolus at the time of 
birth; they appearabout the mnth month, 
and last during life; they are also longer 
in wearing down by mastication than the 
others. ‘The first and second have behind 
a small longitudinal ridge, which assists 
them in cutting the alveolus, but which 
is speedily succeeded by a plane surface, 
intended to afford support to the tooth, 
which shoots behind. No other tooth, 
on the contrary, being to succeed the 
third back grinder, it preserves its ridge 
throughout its whole length; but it has 
a small swelling, which hinders it from 
opening the alveolus so quickly as the 
others. All these teeth, during their 
evolution, produce upon the jaw the 
same effect, as an expansive instrument, 
which dilates it unequally, and varies 
the form of it according to the age of 
the animal, and conformably to the 
wants of every period of its life. 
This respectable anatomist has also 
recently published the first volume of 
his “ Recherches d’ Anatomie et de Chi- 
rurgie.” In this work he chiefly treats 
of the eyes, and the diseases to which 
they are subject, and of the exfoliation 
of the bones; he has inserted in it seve- 
ral of the memoirs noticed in former 
reports. But a work, like the present, 
intended for men of science cannot, it is 
justly observed, be properly analyzed in a 
report of this nature. 
M. Cuvier, proceeds next to inform 
us, that he himself continues his re- 
researches respecting the remains of 
those animals, which the revolutions of 
our globe appear to have destroyed. 
Of these he has described five in the last 
six months. 
The bones of the first have been long 
well known, and are found, in great 
abundance near different rivers in North 
America, where they have improperly 
given to them the apellation of mammoth, 
which belongs exciusively to the jfosséle 
elephant so common in Siberia. Of the 
four othe®s, which belong to the same 
genus, but which were not hitherto 
known, two were found in Europe and 
two in North America. 
‘These five animals are characterised 
by having tusks and a trunk, or proboscis, 
Proceedings of Learned Societies. 487 
like the elephant, and having the lower 
jaw furnished with conical points dis- 
posed in pairs. It is from this last 
circumstance, that the generic name of 
mastodonte, or animaux ad dents mam- 
melonées has been applied to them by 
M. Cuvier, 
The labours of this naturalist respectiug 
the fossile bones, so frequently found in 
the plaster quarries near Paris, led to the 
discovery recently made at Montmartre, 
of a very perfect skeleton. It belongs to 
one of the eleven species supposed at 
present to be extinct, and which have 
been described by M. Cuvier. What 
had only been conjectured respecting the 
bones found separately is now fully con- 
firmed by this skeleton, in which they 
still remain in their natural union. 
M. de Beauvois has published the 
third part of his Insectes recueillis en 
Afrique et en Amerique. 
The history of animals, though placed 
at the limits of the physical and moral 
sciences, does not employ alone, in its 
discussions, the theory of the action of 
bodies ; that of tie operations of mind is 
not foreign to this inquiry. 
_ Itis well known, that the nature and 
limits of the intelligence of the brute 
creation have, for a long period of me, 
occupied the attention of metaphysicians, 
though these are points that can only be 
determined by naturalists. 
In this point of view, such. subjects 
afford proper objects of inquiry to our 
class, and for this reason says the lear- 
ned reporter, we heard with much in- 
terest @ memoir upon instinct, or rather | 
against instinct, by M. Dupont de Ne- 
mours, member of the historical class, 
Considerations wholly foreign to the 
subject, formerly rendered such questions 
extremely complicated, while Descartes, 
on the contrary, ran into the opposite 
extreme, by regarding brutes as mere 
machines. 
Did not experience teach us how far 
the spirit of system has sometimes led 
the greatest of men, we might be induced 
to believe, that they were not serious in 
their speculations, or that they had never . 
attended to the habits and manners of 
animals. Be this, however, as it may, 
since philosophers have found it more 
advantayeous to observe nature herself 
than to create an imaginary world around 
them,theyhave returned toa train of think- 
ing on this subject similar to the vulgar. 
No individual possessed of common 
understanding, can hesitate to believe, 
that animals are conscious of their sen- 
gations, aud are determined in their 
actions 
