201

177

the alveolar ridges, in gradually converging to the almost pointed termination of the
mandible, describe the gentlest curves convex upwards and concave outwards. The
lower border of the symphysis (fig. 12 s s ) is smooth and convex from side to side, and
extends in a straight line from the back part of the symphysis obliquely upwards to the
apical extremity of the mandible : the upper surface of the symphysis (fig. 13, s s ) is
deeply and almost angularly excavated. The inner surface of the free portions of the
rami is smooth and gently concave, with a semicircular ridge extending from the
anterior to the posterior subcoronoid perforation. If the foregoing characters, of which
the details will be excused from the rarity of their subject, be compared with those of
the lower jaw of Porphyrio represented in figs. 1, 5, 6, Pl. XLVII., the correspondence
will be found almost perfect : the lower jaw of Porphyrio, however is not a pneumatic
bone and has no perforation for the admission of air.

It is in the comparison of the lower jaw of the Notornis that the difference from the
Maccaw and the Raven, to which a passing reference was made in the description of the
upper jaw, is most strikingly seen. The mandible of the Raven is as much too shallow
as that of the Maccaw is too deep ; and in neither are the characters of the angle of
the jaw or the perforations repeated. And I may briefly state, that after passing in
review all the skulls and mandibles of the birds in the Hunterian and some other
Metropolitan collections, it is only in the Rallidae or the family of the Coots that I have
met with those essential marks of correspondence which have led to the determination
of the affinities of the bird to which the present remarkable fossil cranium in Mr. Mantell's
collection has belonged.

Besides a species of true Porphyrio (P. melanotus, Gould) in New Zealand, there
exists in that island a peculiar and highly interesting form of the Rallidae in which the
wings, although not so rudimentary as in the Apteryx, are nevertheless so restricted
in their development as to be useless for the purposes of flight. This bird is the type
of the genus Brachypteryx*, - a genus as characteristic of New Zealand, as is the Apteryx
itself. In the lower jaw of the Weeka Rail we have the same form of the angular and
articular enlargement, with the vertical triangular posterior facet, the short deflected
and precurved angle, the posterior smaller and fuller oval perforation (w), and the
anterior fissure of the coronoid part of the jaw, but not the opening (u) : the symphysis
is shorter, but the rounded under-part ascends obliquely straight to the pointed termi-
nation of the mandible. There is the same kind of agreement in the upper jaw: the
solid or rostral part of which anterior to the nostril, has the same essential form, viz.,
a very slight and equable downward curve, gradually contacting to the point, which is
rounded off, while the sides are almost vertical. The palatine surface is deeply exca-

* This generic term was applied by me to the bird represented by the skeleton (No. 1280) in the Museum
of the Royal College of Surgeons the term 'Brachypteres' having been applied by Cuvier to a family of his
Palmipedes ('Regne Animal,'1829), vol.i. p. 344. I adopt the term Ocydromus, as restricted by G.R. Gray,
to the New-Zealand forms of the Ocydromus of Wagler.
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