2i8 Mr. Corse’s Observations on the 
ther advanced in years ; (Tab. VI. and VII.) and it is probable, 
that this canal or sinus between the different alveoli, admits the 
passage of an elongation of the membrane, from the anterior to 
the posterior grinder. 
The time requisite for the complete formation of one of these 
cases of teeth, constituting a grinder, varies from two to six or 
eight years ; and, when an elephant has attained its full size, a 
considerable number of the anterior laminae must be worn 
away, and the fangs absorbed, before the posterior ones can be 
sufficiently advanced to cut the gum. (Tab. VII. X. and XII.) 
From the curved line in which the grinders of the upper 
jaw advance, it must be evident, that some of the anterior la- 
minae must be obliterated, before the last can come into use: 
this may be made to appear more clearly, by drawing lines pa- 
rallel to the surface of the grinder (Tab. VII.) of the upper 
jaw; and is plainly shewn in Tab. X. where the three ante- 
rior laminae are worn down to the fangs ; yet there are ten of 
the posterior ones that cannot (as is evident from their convex 
surface) come into action, till the same number of their pre- 
decessors are worn away in regular succession. Before this 
could have happened, several years must have elapsed, during 
which, the posterior laminae would have been completed ; for, 
in the present state, the three aftermost layers are not even 
now attached to each other, or to the rest which are anterior ; 
the membrane between, and connecting these laminae, not be- 
ing ossified at the time of the animal’s death. In this grinder, 
there are twenty-three laminae, which is the greatest number I 
have seen. 
In the lower jaw, the same circumstances take place; the teeth 
of the grinders rise by the addition of their fangs, force their 
