the malleus ancliylolcd with the tympanum, we can hardly 
conjecture its ule. '1 he other has its origin from the inner 
lurface of the tympanum, and pa fling backwards is inferted 
into the (tapes by a tendon, in which I found a bone in the 
large Bottle mole. This mufcle gives the (tapes a lateral mo- 
tion. What particular ufe in hearing may be produced by 
, the action of thele mufcles, 1 will not pretend to fay; but we 
muft l’uppofe, whatever motion is given to the bones mud 
terminate in the movement of the ftapes. 
The immediate organ of hearing is contained in a round, 
bony procel's, and con (ills of the Cochlea and Semicircular 
Canals, which fomevvhat referable the quadruped ; but, befides 
the two lpiral turns of the cochlea, there is a third, which 
makes a ridge within that continued from the foramen rotun- 
dum, and follows the turns of the canal. 
The cochlea is much larger, when compared with the femi- 
circular canals, than in the human fpecies and quadruped. 
We may reckon two pafl'ages into the immediate organ of hear- 
ing, the foramen rotundum, and foramen ovale. They are at a 
greater diftance than in the quadruped. The foramen rotundum 
is placed much more on the outer furface of the bone, and not 
in the cavity of the bony tympanum; but may be faid to com- 
municate with the furrounding cellular part of the tympanum. 
The foramen rotundum, which is the beginning of one of 
thefe turns, appears to be only one end of a tranfverfe 
groove, which is afterwards clofed in the middle, forming a 
canal with the two ends open ; fo that this foramen appears 
to have two beginnings; but the other opening is probably 
only a palfage for blood-veflels going to the cochlea. 
From 
