PROF. W. K. PARKER ON AGITHOGNATHOUS BIRDS. 298 
a. Direct, as in the Falcons and Geese, when the maxillaries meet below at the 
mid line, as in the mammal: two subvarieties of this form occur, as in the Falcon, 
where the nasal septum is ankylosed to this hard palate; and in the Goose, where it 
remains free. 
b. Indirect.—This is very common and is best seen in Eagles, Vultures, and Owls; 
the maxillo-palatines are ankylosed to the nasal septum by their inner margin, but 
are separated from each other by a chink; this is well seen also in the fledgeling of 
the Falcon, which is indirectly desmognathous at that early stage. 
c. Imperfectly direct.—This is when the maxillo-palatine plates are united by 
harmony-suture, and not by coalescence. Example Dicholophus cristatus. 
d. Imperfectly indirect—Here the maxillo-palatine plates are closely articulated 
with and separated by the “ median septo-maxillary ” bone, but these are not ankylosed. 
Example Megalema asiatica. 
A fifth variety might have been added, in such a case as Podargus, where the 
palatines as well as the maxillaries largely coalesce below; to a less extent this is seen 
in the gigantic species of Hornbills, e. g. Buceros birostris (see Huxley, tom. cit. p. 446, 
fig. 28). 
Podargus carries this desmognathism to the greatest extent of any bird; in the 
Crocodile, and in the Anteater, a still more extended hard palate occurs, where the 
internal pterygoid plates form a lower bridge. 
The unpublished materials from which I have made these extracts illustrate several 
forms of desmognathism, besides the early conditions of the egithognathous palate 
and such schizognathous forms as Zrochilus and Caprimulqus. 
I have already given several figures of the schizognathous palate in my former 
paper, “On the Gallinaceous Birds and Tinamous” (Trans. Zool. Soc. vol. v. pl. 40). 
Here pl. 37 illustrates Syrrhaptes and Lagopus, and pl. 38 Vanellus and Columba; 
pl. 40 gives the struthious or dromeognathous face of Tinamus. But the most familiar 
and simple illustration of the schizognathous face is seen in the Fowl (Phil. Trans. 
1869, pls. 81-87). 
These details of morphology have to be mastered before the taxonomic value of 
these facial characters can be known, or in any way appreciated; and they are matters 
that lie somewhat deeper than the length or thickness of a primary quill, or the 
direction of the outer toe. 
The materials out of which the egithognathous face has been formed, exist, in a raw 
state, in the reptiles (Lacertilia, Ophidia) and, still nearer home, in the Rhea. 
The counterparts of the cartilages in which the first osseous centre for each “ yomer’ 
is found in the ‘‘ A‘githognathz,” were long since figured by me in the Rhea (Phil. 
Trans. 1866, pl. 10. fig. 14, alate sections on each side of r.b.s and v), and also were 
found in the common Snake (Natrix torquata) and in the embryo of Eunectus murinus; 
these studies of the Ophidian face have not, however, been published. 
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