AMERICAN WHITE PELICAN. 95 
PELEcanus AMERICANUS. 
Adult Male. Plate CCCXI. 
Bill a little more than thrice the length of the head, rather slender, 
almost straight, depressed. Upper mandible linear, depressed, convex 
at the base, gradually flattened and a little enlarged to near the end, 
when it again narrows, and terminates in a hooked point. The ridge is 
broad and convex at the base, becomes gradually narrowed and flat- 
tened beyond the middle, is elevated into a thin crest about an inch 
high, of a fibrous structure, and about three inches in length (in some 
specimens as much as five inches) which is continued forwards of less 
elevation to the extent of an inch farther. The ridge of the mandible 
is then narrow and flat, and terminates in the unguis, which is oblong, 
slightly carinate above, curved, obtuse, concave beneath. The edges 
are very sharp and a little involute ; the lower surface of the mandible 
has a median slender sharp ridge, on each side of which, at the dis- 
tance of a quarter of an inch is a stronger ridge having a groove in its 
whole length; the sides then slope upwards to the incurved margin, 
and in this latter space is received the edge of the other mandible. 
Lower mandible having its crura separated, very slender, elastic, and 
meeting only at the very extremity, so that the angle or interspace 
may be described as extremely long, occupying in fact the whole length 
of the bill excepting four-twelfths of an inch at the end ; for two-thirds 
of its length from the base, the lower mandible is broader than the up- 
per, which is owing to the crura lying obliquely, but beyond the crest 
it is narrower ; the extremely short dorsal line ascending, convex, the 
edges inflected, sharp, and longitudinally grooved. To the lower man- 
dible, in place of the skin or membrane filling up the angle in most 
other birds, is appended a vast sac seven inches in depth opposite the 
base of the bill, and extending down the throat about eight inches, so 
that its length from the tip of the lower mandible is twenty-one and a half 
inches, It is formed of the skin, which is thin, transparent, elastic, ru- 
gous, highly vascular, and capable of being expanded like a net, supported 
by the elastic mandibles to the breadth of nine and a half inches. 
Head small, oblong; neck long, stout ; body full, rather flattened. 
Feet short and very stout; tibia bare at its lower part, covered all 
round with small scales ; tarsus short, very stout, compressed, covered 
all round with hexagonal seales, of which the anterior are much larger ; 
