Cu. I.] OF THE DODO. 73 
The mandible thus presents a subtriangular surface, of greater or less extent, and more 
or less tumid, which is covered by the palatal membrane; it is continued backwards by 
the external fibrous wall of the subocular cell, extending from the root of the zygoma to the 
free outer margin of the palatine crest. The surfaces of opposite sides, separated mesially by 
the posterior nares, form a wedge subsiding anteriorly towards the nasal orifice, and descending 
between the rami of the lower jaw, which are so curved that their convexity mounts into 
the obtuse angle formed between the zygoma, and the lower margin of the lateral facet of the 
maxilla; which is indicated in the Dodo by the upper caruncular ridge, separating the palatal 
mucous membrane from the cere, and extending forwards to the lower angle of the nostril. 
In those grallatorial and aquatic birds, as the Ibis, Spoonbill, and Albatross, which have a 
similar arrangement, the margin of the upper mandible overhangs that of the lower; and in 
the Albatross the posterior part of the dentary bone is lodged in a deep groove, between the 
palatine wedge and the acute margin of the mandible. 
IV. The absence of an ossified vomer separating the posterior nares ; this is also generally 
deficient in the Gallinze ; in the Vulturide it exists in the form of a narrow lanceolate plate, 
but is wanting in Cathartes. 
V. The septum narium is generally membranous in Pigeons ; it exhibits however traces 
of ossification at its attachment above, in the Calenas nicobarica, and Lopholemus antarcticus ; 
in the Vulturide it is wholly ossified, a small perforation only existing in certain species; in 
Cathartes it exists, although reduced in length, by the removal of its anterior part in the 
formation of the common nasal vestibule. In the Dodo it is completely membranous. 
VI. The form of the palatine bone in Pigeons is characteristic, and differs from that in the 
Rasores, in the presence of the horizontal plate or crest, which affords an increased surface 
for the origin of the internal pterygoid muscle ; and of the descending palatal process, which 
supports the fold of mucous membrane forming the lateral boundary of the posterior nares. 
In the Vulturidee, the crest is much broader, indicating the greater strength of the muscle 
arising from it; the sphenoidal plate is narrower from the unexpanded condition of the 
rostrum ; the nasal process is much contracted longitudinally, whereas in Pigeons it extends 
forwards along the inner margin of the palatine stem, to near its attachment; the palatine 
process is less elongated, and the inflected portion of it, in Pigeons, is entirely absent ; the 
palatine stem is straight in Vultures, arched with the concavity inwards in Pigeons. In 
Cathartes the stem is also curved; the nasal process is more extended than in Vultures, but 
less elevated than in Pigeons; the crest however indicates the raptorial character by its 
great breadth. 
We shall afterwards see how the form of this bone, in the Dodo, is modified by the 
compression of the mandible and the abbreviation of the rostrum, without departing from 
the Columbine type. 
VII. The shape of the inferior articular surface of the tympanic bone, although it varies 
in different genera of the Columbide, is distinguished from that in the Vulturide, by the 
