28 AMERICAN WHITE PELICAN. 



nation of several individuals in stating, is destitute of the horny crest 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 4-£- inches long, the right abdominal 

 A\ by 4; the left abdominal 5^- by 4; the clavicular cell is not formed by a 

 single cavit3 ? , but of numberless cellules, like those of the subcutaneous tissue. 

 The heart n is triangular, pointed, 3 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, o, being 4 inches in length, and 2\ in 

 breadth, while the left, p, is only 2 inches long, and H inches broad. 



The mandibles are entirely covered with skin, of which the subcutaneous 

 tissue is wanting, the cutis condensed, and the cuticle in large irregular 

 longitudinal plates, leaving the surface somewhat rough and scaly. The 

 crest-like excrescence on the ridge of the upper mandible is not formed of 

 bone, nor otherwise connected with the osseous surface, which is smooth 

 and continuous beneath it, than by being placed upon it, like any other part 

 of the skin, and when softened by immersion 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 longi- 

 tudinal on the broadened ridge; these fibres being continuous with the cutis 

 and cuticle. 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 cuticle, 

 beneath which is the cutis, extremely thin, and with the cuticle thrown into 

 longitudinal rugae 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, composed of two sets of very 

 slender muscular fibres, separated from each other, and running in two oppo- 

 site 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 gradually more forwards, and spreading out, reach the middle 

 line of the pouch. The inner fibres have the same origin, and pass in a con- 

 trary direction, backwards and inwards. From the hyoid bone to the junc- 

 tion of the two crura of the mandible, which takes place almost at the very 

 tip, there extends a thin band of longitudinal muscular fibres, in the centre 

 of which is a cord of elastic tissue. By means of this apparatus, the sac is 

 contracted, so as to occupy little space. When the bill is opened, the crura 

 of the lower mandible separate from each other to a considerable extent, by 

 the action of the muscles inserted into their base, this depending upon their 



