SKULL OF THE ZGITHOGNATHOUS BIRDS. 261 
is elegantly undulating in form. The large postpalatine keels terminate below, in front, 
in a blunt interpalatine process (pt.pa, i.pa@) ; a strong ligament binds the retral maxillo- 
palatine (mwx.p) to this spur. The ethmo-palatine, ankylosed to the vomer, does not 
reach further forward than the isthmus and interpalatine, and is out of view below. 
The parasphenoid (pa.s) is uncovered from the solid part of the vomer to near the end 
of the palatines ; but these close in where they meet the pterygoids. The widest part of 
the maxillary is fenestrate, as in the last instance; but the maxillo-palatines have not 
so long a pedicle, have no spur where they underbind the vomer, and are thick enough 
to contain air-cells (figs. 3 & 4, v, ma.p); their whole form is strongly arched, the 
roundest part of the bow being at their root. As in the last, the vomer is but little 
emarginate, a strong contrast to that of the Nectariniide (Plate LIII.); and I 
strongly suspect that it was ossified from four centres, the two outer being the septo- 
maxillaries. The whole bone is oblong, smooth, and, in front, slightly carinate ; its 
shoulders are grafted upon the inturned lamina of the nasal wall (n.w). The out- 
bowing of the bony bars exposes more of the nasal labyrinth below (n. w, a@.¢b) than in 
the last instance; it is entirely unossified. The septum (s. 7) is long, deep, and non- 
alate ; and the recurrent lamina is hidden by the median part of the preemaxillary mass. 
This skull, generally, is like the last, but has less resemblance to that of the Trochi- 
lide ; its ethmoidal masses (e.eth, p.p) are, like those of Acanthorhynchus, very large and 
spongy, showing no os uncinatum or lacrymal; and over the pars plana the olfactory 
and orbito-nasal nerves pass through one common large space. 
I found the syrinx very perfect in this bird. 
Example 36. Skull of Sericornis humilis (?). Family Sylviide. Section Oscines?!. 
Habitat. Australia. 
This bird and the next are Australian; then I have to describe several from 
Panama and the Central-American district. All these, with two species of the Austra- 
lian genus Petroica, described in the first Part (plate lx. figs. 9 & 10), come, as to their 
skull, under one category, however the zoologist may find it necessary to put them into 
various families. 
Some of them have a “syrinx;” and in others it is not developed; but as to their 
skull, they have much in common, and they are evidently intermediate between the 
soft-billed Passerines with which we are familiar here, such as Sylvia, Muscicapa, Mota- 
cilla, Anthus, and those of South America, such as Muscisaxicola, Synallaxis, Aneretes 
(Part I. plate lix.), and also the Australian “ Meliphagide,” just described ?. 
? This bird has, I find, a perfect syrinz. 
* I must confess that the latter are much nearer to the Sylviines than the South-American Tyrannide and 
Dendrocolaptidx ; the most archaic Australian type is Menura (Part I. plate lvi.). The Whinchat (Pratincola 
rubetra) corresponds very closely with the Central-American types (see Plate XLVIIL.). 
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