OBSERVATIONS ON THE ANATOMY OF 
tion exterior to the integuments, yet a tolerably perfect 
concha exists immediately beneath them. The longitudinal 
aperture by which the ear opens on the integuments is 
situated immediately behind the eye, and not far from the 
posterior or floating edge of the flap of the bilL The hairs 
are disposed around this aperture, as the feathers around 
the ear in birds. There is nothing peculiat in the aperture 
itself as to muscles, &c., but it opefns immediately into a 
considerable cavity, formed by a cartilaginous plate, dis- 
posed after the manner of the concha of the Mammalia^ 
and which we must consider as the true external ear of the 
animal, though it be not external to the integuments. The 
cartilaginous plate is fixed, on the one hand^ to the long 
tube, connecting it with the cavity of the tympanum, andj 
on the other, in a very loose manner, to the superjacent 
integuments. Distinct muscles are attached to it, as in the 
Mammalia, which have the concha situated externally. 
These arise from the panniculus carnosus, and are inserted 
into the concha : there can be little doubt, that^ by their 
action, and the loose attachment of the cartilage of the ear 
to the integuments, considerable motions are performed by 
it,— ^the object of which must be to increase the general 
cavity formed by the concha, and cartilaginous tube of the 
ear, and in some measure to increase the size of the exter- 
nal aperture. Nearly one half of the external opening of 
the ear is formed by the edge of the cartilaginous tube ; 
the common integuments form the I'emaining half, because 
the cartilage properly called Concha is thrown back under 
the integuments, having an extensive margin attached 
slightly by cellular tissue to the integuments, completing, 
in this way, the circle of the meatus externus. We thus 
see that there is a certain degree of inaccuracy in stating 
that the Ornithorynchus has no external ear ; and that it 
should be said that it has no ear externally, since a tolerably 
