AMERICAN WHITE PELICAN. 97 
examination of several individuals in stating, is destitute of the horny 
erest of the upper mandible. 
A male, shot near Grande Terre, in the Gulf of Mexico, examined. 
The skin is very thin, but the subcutaneous cellular tissue is extremely 
developed, forming a thick reticular layer over the whole body. The 
internal cells are also of vast size, the right hepatic being 43 inches 
long, the right abdominal 43 by 4; the left abdominal 54 by 4; the 
elavicular cell is not formed by a single cavity, but of numberless 
cellules, like those of the subcutaneous tissue. The heart » is trian- 
gular, pointed, 8 inches long, 2 inches and 10 twelfths in breadth ; 
the aorta branches at the base, as in other birds, sending off the two 
trunks which separate into the subclavian and carotid. The lobes of 
the liver are extremely unequal, the right, 0, being 4 inches in length, 
and 2} in breadth, while the left, p, is only 2 inches long, and 1; inch 
broad. 
The mandibles are entirely covered with skin, of which the subeu- 
taneous tissue is wanting, the cutis condensed, and the cuticle in large 
irregular longitudinal plates, leaving the surface somewhat rough and 
sealy. The crest-like excrescence on the ridge of the upper mandible 
is not formed of bone, nor otherwise connected with the osseous sur- 
face, which is smooth and continuous beneath it, than by being placed 
upon it, like any other part of the skin, and when softened by immer- 
sion in a liquid may be bent a little to either side. It is composed 
internally of erect slender plates of a fibrous texture, externally of 
horny fibres, which are erect on the sides, and longitudinal on the 
broadened ridge ; these fibres being continuous with the cutis and cu- 
ticle. ‘The skin of the mandible is continuous with that of the pouch, 
of which the structure is as follows. Externally there is a layer of cu- 
ticle, beneath which is the cutis, extremely thin, and with the cuticle 
thrown into longitudinal rug when contracted. The internal surface 
is also of cuticle, and beneath it is a layer of cutis. Between these 
two very thin layers of skin, is interposed an equally thin layer, com- 
posed of two sets of very slender muscular fibres, separated from each 
other, and running in two opposite directions. The outer fibres run 
in fasciculi from the lower and inner edge of the mandible; those from 
its base pass downwards, those arising more anteriorly pass gradu- 
VOL. lv. G 
