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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 Rallide 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 Rallide 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 contracting 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 ‘ Brachyptéres’ having been applied by Cuvier to a family of his 
Palmipédes (* Régne Animal,’ 1829), vol. i. p, 344. Ladopt the term Ocydromus, as restricted by G. R. Gray, 
to the New-Zealand forms of the Ocydromus of Wagler. 
AA 
