THE TURBINATED BONES IN BIRDS. 281 
More than one hundred minute ramifications, by no means incon- 
siderable in size, were counted on one of the eight. 
On viewing the bone in profile, it appeared that these ramifica- 
tions were not merely osseous spiculse, but the minute edges of 
bony plates of exquisite tenuity, about one inch in length, and 
one-twentieth of an inch in breadth. These laminse pass back- 
wards, and, subdividing themselves before their re-union, termi- 
nate in a bone which is situated in the back part of the nostril. 
The extreme ramifications approach very closely to the septum , the 
os palati , the os maxillcire, and the orbit of the eye, but without 
contact. 
The olfactory membrane with all its nerves is closely applied to 
every plate of this astonishing assemblage of laminse, as well as to 
the main trunk, and to the internal surface of the surrounding cavity. 
It would be extremely difficult, not to say impossible, to calculate 
the superficial surface of this membrane. If we take one hundred 
as the average number of lamellae on each branch, the whole num- 
ber will be 800, and the two surfaces will be represented by 1600. 
To this we must add, at least 800 for the surface of the remaining 
portions of the ramified bone and the cavity. In all, there are 2400 
surfaces of about one inch in length, and one-twentieth of an inch 
in breadth, or 120 square inches in each nostril*. The olfactory 
organs of the animal must, consequently, be possessed of exquisite 
sensibility. There are no terrestrial animals that have yet been 
subjected to examination, in which there is any thing comparable 
with this, with the exception of the otter, but he equals not the seal. 
The seal has the peculiar faculty of closipg the nostril at plea- 
sure. This is beautifully seen in the seal now in the menagerie of 
the Zoological Society of London. An organ of such exquisite 
sensibility required an extraordinary power of securing itself from 
injury by the voluntary exclusion of noxious matter. 
Birds . — I have already described the origin of the olfactory 
nerves in some of our domesticated birds. As they proceed from 
the anterior apex of each hemisphere, there is no cribriform or 
sieve-like process for them to perforate, but they pass undivided 
through certain foramina in the cranial bone. Sometimes their 
passage can be readily traced, and then they will be seen proceeding 
through the orbit of the eye, and, within that orbit, bifurcating, and 
the two trunks of each passing on, and distributing their ramifica- 
cations on the upper and lower mandibles. The texture, however, 
of these nerves is exceedingly soft and pulpy, and the path of the 
nerves is not always to be traced until they have proceeded a cer- 
tain distance from their origin, when they will be plainly enough 
VOL, XII. 
* Harwood, p. 23 
P p 
