XX 
INTRODUCTION. 
iDost birds, is divided into two unequal lobes by a pellucid membrane; each 
of these lobes rests on one of the sides of the body ; the hepatic duct 
opens separately from the cystic, and its termination is sometimes preceded 
by pancreatic ducts, though often by a single one alone. Nor do all birds 
possess a gall-bladder. In the Osprey and Misselthrush it is large, and 
nearly oval, in the Sparrow extremely small, and in many of the species, as 
in the Pigeon, it is entirely wanting. Similar remarks extend to the spleen, ** 
which is found in many of the species and denied to others. 
The little valve, or membranous covering of the orifice of the wind- 
pipe, called the epiglottis, though common to man and quadrupedes, is not 
given to birds ; but in its stead, at the upper extremity of the trachea, or 
windpipe, a rima glottidis, with muscular sides, acts to prevent the food 
and drink from passing into the lungs ; and, besides this precaution, several 
stiff, sharp papillae guard its entrance ; which, in the Wheatear, are black, 
in the Rook, greenish blue, in the Swallow, yellow, in the Goatsucker, light 
brown. The trachea itself is not firmly fixed to the vertebrae, as in men 
contrivance to take place, the animal’s wings would be unable to sustain it in the air ; because the 
length of the layers, or rays, would of course weaken their strength, and offer a slighter resistance 
to the atmosphere, and in the rapidity of flight, would frequently furl backwards, and permit the 
air to pass between the quills : the shortness of the outer web would be insufiicient to fold over 
the adjacent feather, and the whole wing be permeable. 
’’ The lobes of the liver of the Osprey are of equal size and weight, and to them is added 
what is rarely found in birds, a smaller lobe, resembling the lobulus spigellii in the human, 
race. 
** In some birds, the spleen is of a globular figure, as In the common fowl, but In the Rook 
it is of a lozenge form, and nearly two inches in length, and of a purplish hue. In the Osprey 
it is scarcely an inch long, and in the Pigeon it does not exceed a quarter of an inch, and in shape 
is of an oblong oval. It lies near the bulbus glandulosus, and the pancreas, the latter of which is 
of considerable size In carnivorous birds, of different form in many of the species, but generally 
wearing a twofold appearance. 
