300

270

the same relative extent in Apteryx as in Dinornis ; and the confluent anterior part of
the vomerine lamellae in Apteryx probably indicated the true condition of the vomer in
Dinornis. In Dromaius the non-united halves of the vomer diverge posteriorly in a
greater degree than in Apteryx or Dinornis, exposing a greater proportion of the
rostrum. The obliquely and mesially concave palatal plates converge anteriorly, not so
much or so soon in Dinornis as in Apteryx, but more quickly than in Dromaius, defining
more completely a smaller pair of bony palato-nares. It is more probable that the
detached representatives of "palatines" worked out of the matrix in the first speci-
men, were the parts broken away from the anchylosed union of those bones with the
palatal plates of the maxillary anteriorly, and with the pterygoids behind.

In Struthio, Rhea, and Casuarius the pterygoid coalesces with the palatine earlier
than it does in Dromaius. A greater proportion of the vomer is cleft posteriorly in
Dromaius than in Rhea. Upon the whole Dromaius, among the larger existing Stru-
thionidae, makes the nearest approach in palatal structure to Dinornis and Apteryx.
This closer affinity is shown in the form of the basioccipital-sphenoidal tract and its
relation to the pterapophyses. In Rhea, which, after Dromaius, comes next in palatal
conformity, the tract in question sinks abruptly below the level of the pterapophyses,
which seem to diverge at almost a right angle from the base itself of the rostrum.
In Dromaius the pterapophyses diverge from the fore part of the tract itself, which
is on the same level with the back part of the tract, and, as in Dinornis, only distin-
guished therefrom by the lateral constrictions or grooves due to the pressure of the
Eustachian tubes.

The appreciation of the near affinities, among Struthionidae, of Dromaius to Dinornis
and Apteryx led me to select the skull of the Emu to illustrate that of the Moa in my
first attempts to restore that complex and instructive part of the skeleton of the huge
extinct New-Zealand apterous birds 1.

The results of the above exposition of palatal structure in the skulls of Dinornis
crassus have enabled me to restore, from cranial fragments in the Walter-Mantellian
series, not only the pterygoids and portions of the palatines of Dinornis crassus, but
also those of the Dinornis ingens as figured in Pl. LXXXII. fig. 3.

In Dinornis crassus the malar process of the maxillary (Pl. LXXVI. fig. 1, 21), the
malar (ib. 26), and squamosal (ib. 27) have coalesced into a styliform zygoma 2 inches
2 lines in length. The malar rises as a low, obtuse ridge toward the postfrontal ; the
squamosal has a rough elliptic surface at the inner side of its hinder end, which pro-
jects inward to an obtuse point effecting the "gomphosis" with the tympanic (28). This
bone (Pl. LXXVI. figs. 5 & 6), in relation to the shorter mandible, is relatively as well
as absolutely smaller than in Dinornis elephantopus ; the orbital process (k) is more
triangular, has a broader base than in Dinornis elephantopus : this process is more

1 Most of the notable notifications of the palate and pterygo-palatine arches have since been figured by Eyton
in the rich storehouse of the bony structure of birds, entitled 'Osteologia Avium,' 4to, London, 1864-67.