PEOF. W. K. PAEKEE ON ^GITHOGNATHOUS BIEDS. 323 



Example 13. Muscisaxicola mentalis. 



Habitat. Chili. Group " Tracheophonse," Miiller ; family " Tyrannidee." 



This is a larger bird, and has a stouter face than the last ; yet, on comparing the 

 palates together, it is easily seen how near they are in nature. The character of the 

 bony substance in the two is exactly alike, both in the cellular and in the fibrous parts ; 

 it is of the most delicate kind. The basitemporal projects more at the mid line under 

 the Eustachian opening (PI. LIX. fig. 9, b.t, eu) ; and the posterior part of the para- 

 sphenoid (pa.s) is not so thick. The hinge-notch is more perfect than in Synallaxis, 

 and the septum much deeper and more largely alate (PI. LIX. figs. 9 & 10, tr) ; it much 

 resembles that of Jlomorus (see PI. LX. figs, 1-4), but it is deeper, as in Dendrocolaptes 

 (PI. LIX. fig. cijS.n). The alse nasi are soft externally; but their turbinals are ossified 

 (fig. 9, a.th), as is also the nasal floor {n.f.) and part of the recurrent fold [re. c). 

 The inferior turbinals have patches of endostosis. On the whole, the anterior part of 

 the palate is very much ossified for so small a bird. The vomer is large (figs. 9 & 10 v)\ 

 and the inturned lamina [i. a. I), like the alinasal turbinal, is ossified by its own endosteal 

 deposit, and articulates with the large swollen lobes of the vomer — that is, with its 

 coalesced septo-maxillaries : this belongs to the 1st variety of " complete desmognathism." 



The bony septum, behind its large subnasal alsc. is very solid and even bulbous ; and it 

 is almost embraced by the still more bulbous upper lobes of the vomer. The vomer is 

 broad, flat, largely united at the mid line ; and its flat crura are near together, and anky- 

 losed to the ethmo-palatines. 



The likeness and the unlikeness of the next arch in this type and in Synallaxis is very 

 instructive, as showing very fine, and yet quite measurable and evident diversity. The 

 delicate, arcuate, ascending apex of the pterygoid {e.pg) has here its fullest oinithic 

 growth; the whole pterygoid (fig. 9,j)(/) is longer, more arcuate, and clings more closely 

 to its fellow in front, where it sends upwards a flat, leafy lobe, which articulates in 

 front with the mesopterygoid lobe of the palatine, once a separate bone. 



The postpalatine laminae are cut away, as it were, below ; and the body of the bone 

 is more spongy than in Synallaxis; the prsepalatal bars are equally delicate, and form 

 one continuous and almost straight bar with the edge of the broad part and the retral 

 transpalatine [t.pa). The ethmo-palatal is dome-shaped, as in all these types. 



The investing bones are all ankylosed together ; the maxillo-palatines (figs. 9 & 10, 

 mx.p) are like pruning-hooks, and are somewhat pedunculate. 



The ecto-ethmoid is squarer than in Synallaxis, its outer side being less concave, 

 and its angle less developed ; it is a flat, spongy plate, appearing moderately above, 

 and having over its antorbital region a huge doorway from the orbit into the nasal sac, 

 through which both kinds of nerve pass. 



Example 1 4. Ilomorus unicolor. 



Habitat. Mendoza, La Plata. Group " TracheophonEe," Miiller ; family " Dendroco- 

 laptidse." 



2 .X 2 



