SKULL OF THE HGITHOGNATHOUS BIRDS, 297 
the maxillary has its largest development. It is noticeable here that in this respect a 
Sauropsidan type which is the furthest removed from the lower cold-blooded forms by 
intense metamorphosis, yet has, for prehensile purposes, its fore face brought back 
into greater harmony with them than is seen in birds generally. Here the dentary 
edge of the premaxillary (d.px) reaches halfway to the gape-angle of the maxillary 
(ma), and this latter bone forms a large and sinuously vaulted roof to the outer third 
of the fore palate. At the widest part of this plate it sends inwards and backwards 
the maxillo-palatine sickles (ma.p); and these also are peculiar. These delicate, cres- 
centic, flat spurs come nearest to those of certain South-American Coracomorphe, é. 4. 
the “tracheophonous” Synallaais (Part I. pl. lix. figs. 6 & 7, map); and this is a 
reasonable thing, that a harsh-voiced outlier of the Passerines should approach some 
less-modified type of the group itself. In Caprimulgus they have the same form, are 
much like those of the “ Dendrocolaptide ” and “ Formicariide,” but are short and 
spongy. 
The vomer (figs. 1 & 3, v) is an extraordinary bone, although absolutely Passerine. 
In the adult the “ body ” is only one fourth the length of the bone: it is more like the 
face of a fox than of an 02; and its sharp outstretched ears are formed by the extension 
of bony matter into the inturned alinasal lamina (?. a/); they are not evidently separate 
as septomaxillaries (s.mx). The fore margin of the vomer is rounded, and not scooped ; 
and the inferior surface is gently convex. ‘The bone narrows in rapidly; and the crura 
are very near at first, but open out, like callipers, behind, exposing the overlapping 
ethmo-palatine spurs on their inner face (figs. 1 & 3, v, e.pa). 
In old birds the septum nasi, which is well notched off from the far-projecting eth- 
moid, becomes bony aboye, the alinasal and inferior turbinals become largely calcified, 
but the al outside remain soft. Clinging to the upper two thirds of the descending 
crus of the nasal is a spongy pupiform lacrymal, which is smaller in the older birds 
than in those of the first summer. 
With one exception in these examples, namely Menwra, the Coracomorphe expose 
their ecto-ethmoid after the manner of an ordinary Fish, a Monitor, or a Crocodile. 
So do the Swallows, quite normally; but in the Swift the fore part of the frontal forms 
an overhanging eave to that bone—the first step thus to that hiding away and abortive 
development of this part seen in Vodargus and its desmognathous relations. The 
Goatsucker lies midway between the Swift and those types. In the Swift, as in the 
Goatsucker, the pars plana runs into the skull above, and the foramen for the olfactory 
crus is neat and distinct; but the orbito-nasal nerve grooves the outside of the over- 
roofed ecto-ethmoid, and does not perforate its mass: this is a non-Passerine character, 
a delicate test of the distance we have gained from that group. The whole of the outer 
ethmoid is spongy and thick, and of a squarish form—the outer margin, however, being 
convex, and the lower sinuous. In Caprimulgus (op. cit. pl. 21. fig. 8) the pars plana, 
