5 
I am not aware that in any other species of bird there is the same difference in the re- 
lative length of the bill, as compared with its breadth, in the two sexes’. 
The soft integument of the head is continued over the base of the bill, and extended 
along each side, in the form of a narrow angular process, as in the larger Struthious 
birds. ‘The lateral and a greater portion of the upper part of, this integument are 
covered with short stiff plumes, directed forwards, with long slender black bristles in- 
termixed, and projecting in various directions. The naked part of this integument or 
eere® presents a peculiar form, being deeply emarginate both before and behind; the 
middle portion measures 14 line in the longitudinal diameter ; that of each lateral por- 
tion is 9 lines: the transverse diameter of the cere is 4 lines ; from the gape to the apew 
of the lateral process of plumed integument is | inch 8 lines. From this apea two nar- 
row grooves extend along the side of the upper mandible, nearly parallel with the tomia ; 
the upper groove is continued into a subcircular furrow sculptured on the deflected trun- 
cate tip of the mandible ; the lower groove leads into the external nostril®, which forms 
the dilated termination of this groove ; the nostrils, as is well known, are most singularly 
situated, within one-eighth of an inch of the extremity of the slender elongated mandible, 
An angular process of plumed and bristled integument, narrower than that above, 
extends forwards upon each side of the lower mandible to the distance of 8 lines from 
the gape. A groove is continued forwards from the apew of this process, and expands 
into a shallow depression as it proceeds. The lower mandible becomes gradually nar- 
rower and flatter to its apea; its entire length in the male was 5 inches 3 lines ; each 
ramus is articulated by two trochlear cavities to two corresponding convexities on the os 
quadratum ; from the posterior extremity to the point of confluence of the two rami mea- 
sures 3 inches ; from this point two linear impressions extend forwards, slightly diverging 
from each other, until about halfa line from the tomial margin, nearly parallel with which 
they are continued to the end of the mandible, This part is obtusely rounded, and is 
opposed to the posterior concavity of the deflected and expanded tip of the upper man- 
dible. Thus when the Apteryx rests its head upon its beak, the extremity of which then 
presses upon the ground,—a not unusual posture, as I am informed,—the superincum- 
bent weight is transferred by both mandibles to their proximal extremities : when, also, 
the beak is thrust into the ground in quest of food, the force of both jaws is concen- 
trated upon the smooth and dense wedge-shaped extremity of the upper mandible, and 
the earth is less liable to be forced between the mandibles than it would have been if 
the anterior opening had not been defended by the deflected tip of the upper one, 
' In other classes we meet with examples of a considerable difference in the development of the jaws as a 
sexual character; thus, in Mammalia the jaws of the male Cachalot have more than twice the length, both re- 
lative and absolute, of those of the female. In Insects the Lucani are familiar examples of a still more diepro- 
portionate development of the mandibles in the male; in the Apteryx the difference in the development of the 
jaws, if sexual, is the reverse, the excess being in the female, and this would correspond with the sexual supe~ 
riority in size and strength in the females of the Raptorial Birds. 
t Pl, I, a. Fig, 2. 5 Pl. I. a. Fig. 1. 
. 
