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6

If the beak of the Apteryx be compared with that of the Ibis and Rhea, it will be found
that its plan of construction is precisely that of the Struthious Bird, and that the re-
semblance to the grallatorial beak is confined to the elongated form and slenderness of
its produced anterior part. In the Ibis, for example, the beak is compressed from its
very commencement ; in the Apteryx it is depressed at its base, as in the Rhea. There
is no production of integument, either plumed or naked, upon the base of the bill of
the Ibis, while in the Rhea¹ we find precisely the same structure, but on a magnified
scale, as that above described in the Apteryx ; the naked cere is deeply emarginate, both
before and behind ; the plumed integument has many black setae, but shorter and finer
than in the Apteryx, mingled with the short and stiff feathers. In the Ibis the external
nostrils are pierced in the very base of the beak ; a groove is continued from each nos-
tril to the end of the mandible ; the same grooves are seen in the Rhea, but here the
nostrils open at the anterior angle of the lateral processes of plumed integument, which
are extended along the sides of the base of the bill, as in the Apteryx. In another
Struthious genus, the Cassowary, the nostrils are situated still more forwards, and are
pierced as in the Apteryx, in the horny sheath of the bill itself ; there is no other Bird
which approaches nearer to the Apteryx in the anterior position of the nostrils than does
the Cassowary ; the peculiar modification of the base of the beak in this Bird obscures,
as it were, the resemblance which we might otherwise have been able to trace in that
part. The Emeu and Ostrich correspond with the Rhea and Apteryx in the modifications
above noticed, in the base of the upper mandible. If we examine the lower mandible
of the larger Struthionidae, we perceive a modification of its inferior surface, which di-
stinguishes it from that of any Gallinaceous or Grallatorial Bird ; in the Ostrich the tip
is formed by a raised quadrate portion, separated by two lateral parallel grooves from
the rest of the gnathotheca ; in the Rhea the corresponding raised median piece is longer
and narrower than in the Ostrich, and the lateral boundary-lines converge backwards
to the angle where the symphysis menti commences. In the Apteryx, notwithstanding
the modification by which the bill is transformed from a granivorous to an insectivorous
instrument, we find a middle piece marked out, as in the Rhea, by two grooves diverging
forwards from the angle of confluence of the rami of the jaw². The lower mandible of
the Ibis offers no trace of this character, but is traversed longitudinally by a single mesial
groove.

In the Apteryx a narrow membranous fold or ridge is continued from each angle of
the gape obliquely forwards and inwards upon the slightly convex under or palatal
surface of the upper mandible, and these ridges are gradually lost about 8 lines in front
of the posterior apertures of the nostrils ; these apertures³ present the form of two linear
slits, 4 lines in length, situated close together, parallel with the axis of the beak, and
4 1/2 inches from its extremity, in the male : the common opening of the Eustachian tubes⁴
is situated two lines behind the posterior nares. From the anterior part of these aper-

¹ Pl. I. Fig. 3. ²Pl. VII. Fig. 7. ³Pl. III .a. Fig. 1. ⁴Pl. III. b. Fig. 1.