SKULL OF THE £GITHOGNATHOUS BIRDS. 256 
crept some distance into the end of the inturned lamina of the nasal wall (7.a/). Ido not 
see a distinct septo-maxillary ; most probably this has been already added to the horns of 
the vomer. The extent of the nasal labyrinth is, both in width and length, much 
greater than in Tanagra (compare fig. 6 with fig. 1); but, as in that genus, the trabe- 
cule make the base of the nasal septum alate (fr, s.7). In this, evidently a first-summer 
specimen, the whole labyrinth is soft. And the immaturity of the bird has been of great 
use morphologically ; for not only are the mesopterygoids distinct, but we have also a 
perfectly distinct seed-shaped lacrymal and os uncinatum (fig. 7, /, 0. wv), the former 
capping the projecting ecto-ethmoid, and the latter clamping the foot of the pars plana 
(e.eth, p.p). There is a lunate fenestra in the perpendicular ethmoid (fig. 7, p. é), 
besides the pear-shaped interorbital fenestra, the fore part of which is seen in the figure 
(i. 0. f). Above the ethmo-presphenoidal bar there is, on each side, a huge fenestra, 
which largely occupies the orbital region of the frontal. This is common in small 
Passerines. 
Example 33. Skull of Phytotoma rara. Family Phytotomide. 
Habitat. Chili. 
This type of skull stands out amongst those of the Tanagride more than that of 
Coccothraustes does amongst those of the Fringillide. Yet to the former it is most 
evidently related, although unique in many of its characters, and as a whole a most 
remarkable and evidently ancient form. 
This skull, like that of the Grosbeak, is an isomorph of that of the Parrot, but it is 
not so Psittacine as that of the Old-world bird}. I have purposely placed the figure 
of the palate in this type side by side with that of Tanagra (Plate XLVI. figs. 1 & 8): 
thus their agreement and their disagreement will be plainly seen. 
A general view of the skull shows it to be more like that of a large Finch and less 
like that of a small Crow than the skull of Zanagra. The proportional relation of 
the nasal labyrinth to the hinder palatal region is very small in Phytotoma, medium 
in Tanagra, and very large in Prionochilus (figs. 8, 1, & 6. The unusual length of 
the pterygoids (fig. 8, pg) is Psittacine; and this is correlated with a small and slender 
orbital process of the quadrate, as in the Parrots; but both the quadrate and ptery- 
goids are thoroughly Tanagrine in this rare form. The epipterygoid (e.pg) and the 
dilated fore end of that bone, which has given up a large mesopterygoid piece to 
the palatine (fig. 10, ms.pg, pg, pt.pa), these parts are precisely like those of Zanagra. 
The postpalatine keels (pt.pa) are much larger in this type than in Tanagra and its 
relations, scarcely more so, however, than in Prionochilus (fig. 6). The Parrot-like 
modification of the palatines is most seen in the strong and oblique (not steep) trans- 
1 But that sort of modification by which a conirostral bird of the Passerine type becomes like a Parrot in 
certain respects does not in any way affect its true relationships ;- like the desmognathism of the palate in many 
types, it is a morphological peculiarity, and not a zoological bond of affinity. 
