SKULL OF THE .EGITHOGNATHOUS BIRDS. 255 



crept some distance into the end of the intumed lamina of the nasal wall (i.al). I do 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- 

 culae make the base of the nasal septum alate (tr, s. n). 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, I, o. u), the former 

 capping the projecting ecto-ethmoid, and the latter clamping the foot of the pars plana 

 {e.eth, p .J)). There is a lunate fenestra in the perpendicular ethmoid (fig. 7,^. e), 

 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 Phytotomidse. 



Halitat. Chili. 



This type of skull stands out amongst those of the Tanagridee more than that of 

 Coccothraustes does amongst those of the Fringillidse. 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. 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 Tanagra. The proportional relation of 

 the nasal labyrinth to the hinder palatal region is very small in Phytotoma, medium 

 in Tanagra, and very large in Pnonochilus (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, ptpa), these parts are precisely like those of Tanagra. 

 The postpalatine keels (ptpa) 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 ohlique (not steep) trans- 



' But that sort of modifleation 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. 



