240 COMMON GANNET. 
bladder, n, is very large, of an oblong form, rounded at both ends, 1 inch 
and 8 twelfths long. 
The trachea is 12 inches long, moderately ossified, round, its dia- 
meter at the top 7 twelfths, gradually narrowing to 4 twelfths; the 
rings 124, the lower 4 united. The bronchi are large, their diameter 
greater than that of the lower part of the trachea; of 25 cartilaginous 
half-rings. The lateral or contractor muscles of the trachea are of mo- 
derate strength ; the sterno-tracheals strong ; a pair of inferior laryn- 
geal muscles attached to the glandular-looking, yellowish-white bodies 
inserted upon the membrane between the first and second rings of the 
bronchi. 
‘The olfactory nerve comes off from the extreme anterior point of 
the cerebrum, enters a canal in the spongy tissue of the bone, and runs 
in it close to the septum between the eyes for 10 twelfths of an inch, 
with a slight curve. It then enters the nasal cavity, which is of an ir- 
regular triangular form, 13 inch long at the external or palatal aper- 
ture, 10 twelfths in height. The supramaxillary branch of the fifth 
pair runs along the upper edge of the orbit, and by a canal in the spongy 
tissue of the bones, enters the great cavity of the upper mandible, keep- 
ing nearer its lower surface, and there branching. This cavity appears 
to have no communication with the nasal; nor has the latter any pas- 
sage towards the obliterated external nostrils. The lachrymal duct 
passes obliquely inwards from the anterior corner of the eye, and en- 
ters the nasal cavity by an aperture 4 twelfth in diameter, near its an- 
terior margin. 
In the cloaca was found a solid calculus, half an inch in diameter, 
of an irregular form, white within, externally pale yellowish-brown, 
and marked with grooves impressed by the action of the sphincter ani. 
The digestive and respiratory organs of the American Gannet are 
thus precisely similar to those of the European. In external form, 
proportions, and colours, there are no appreciable differences. The 
young in all stages are similar. ‘The flight, voice, general habits, and 
all other circumstances, are the same. What, then, shall we say to those 
who have pretended that the American bird differs from the European ? 
Merely this, compare the two, outside and inside, shew us differences, 
and then we shall judge if they be sufficient to indicate different spe- 
cies; but until you have done this, do not imagine that a mere “‘ Sula 
Americana Nob.,” is enough to satisfy the world on this or any similar 
point. 
