380 
DR. R. W. SHUFELDT’S MORPHOLOGICAL 
The Heart and Carotids , Trachea , Viscera , Sfc. 
Cypseli as a rule possess but a single carotid, the left one ; 
Professor Garrod, however, discovered that Cypseloules proved 
an exception to this. In Cheetura I found but one, which was 
disposed along the anterior aspect of the neck in the most usual 
manner ; while in Micropus melanoleucus the left carotid, here 
also the only one present, takes on a peculiar course, for being 
so far over to the left, it passes up to the front of the neck 
obliquely, and completely outside the protection of the muscles 
and the hypophysial canal of the vertebrae. 
Past the middle point of the neck, however, it enters between 
the muscles to the aforesaid canal, and then follows the usual 
course to the head. 
Swifts do not possess a heart of any unusual dimensions ; but 
Humming-birds, on the other hand, have a heart quite as unpro- 
portionately large for their size as are the feet of these, the other- 
wise pygmies of the Class. They too have but one carotid, so 
far as I have examined, the left one alone beiug represented. 
MacGillivray, in Audubon’s ‘ Birds of North America,’ under 
the latter’s account of Trochilus colubris, presents us with a very 
good description of the trachea in a Humming-bird. He says of 
it that “ The trachea is 9 twelfths long, being thus remarkably 
short on account of its bifurcating very high on the neck, for if it 
were to divide at the usual place, or just anteriorly to the base of 
the heart, it would be 4^ twelfths longer. In this respect it differs 
from that of all other birds examined, with the exception of the 
Roseate Spoonbill ( Platalea ajaja ), the trachea of which is iu so 
far similar. The bronchi are exactly | inch in length. Until 
the bifurcation, the trachea passes along the right side, after- 
wards directly in front. There are 50 rings to the fork ; and 
each bronchus has 34 rings. The breadth of the trachea at the 
upper part is scarcely more than \ twelfth, and at the lower part 
considerably less. It is much flattened, and the rings are very 
narrow, cartilaginous, and placed widely apart. The bronchial 
rings are similar, and differ from those of most birds in being 
complete. The two bronchi lie in contact for 2 twelfths at the 
upper part, being connected by a common membrane. The lateral 
muscles are extremely slender. The last ring of the trachea is 
four times the breadth of the rest, and has on each side a large 
but not very prominent mass of muscular fibres, inserted into the 
first bronchial riug. This mass does not seem to be divisible 
