ANATOMY OF THE PIGEON. 525 
tine) is long and ends in a cloaca, which receives the ends 
of the urinary canals and oviducts. Attention should be 
given to the trachea ; its bronchial branches, the larynx and 
thesyrinz or lower larynx, which may be developed either 
at the end of the trachea, or at the junction of the trachea 
and bronchi, or in the bronchi alone. The thymus gland 
(Fig. 458, th) is very large and long, while the thyroid (?) is 
a small, oval mass situated at the beginning of the bronchi. 
The following account and drawings of the anatomy of 
the pigeon have been prepared from original dissections by 
Dr. C. S. Minot. As pigeons are one of the most readily 
obtainable and convenient types of birds, the following 
description of the anatomy of a male is given as illustrative 
of the class, those peculiarities being especially noticed by 
which birds are distinguished from reptiles and mammals. 
Before dissecting a bird, it must be carefully plucked ; 
this operation is much facilitated by dipping the animal in 
boiling water for a few minutes. The limbs and muscles of 
one, best of the left, side are to be removed ; the powerful 
pectoral muscles cut off close to their attachment to the 
keel of the breast-bone, and the ribs then cut away, care 
being taken to avoid injuring any of the internal organs, 
most of which .will now be displayed in situ nearly as shown 
in Fig. 459, which represents a dissection carried somewhat 
further. 
The skin (Fig. 459, #, from the neck) is characterized by 
the presence of numerous ridges which cross one another, 
so as to enclose quadrilateral spaces; at the intersections 
of the ridges are small pits in which the feathers are in- 
serted. 
The digestive canal begins in the horny bill with three 
openings, one the large gape or mouth, and two oblique 
elongated nasal clefts (7), through which respiration is or- 
dinarily alone effected. It then extends backward under- 
neath the base of the skull, where it splits into the cwsopha- 
gus and trachea, two large tubes which run down the front 
of the neck, the esophagus on the right and the trachea 
on the left. Just below the head the trachea lies, in its 
normal] position, in front of the esophagus, though in most 
