SKULL OF THE ^GITHOGNATHOUS 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 prsemaxillary (d.pji:) reaches halfway to the gape-angle of the maxillary 

 (nuv), 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 {mx.p) ; and these also are peculiar. These delicate, cres- 

 centic, flat spurs come nearest to those of cei^tain South-American Coracomorphse, e. g. 

 the " tracheophonous " Synallaxis (Part I. pi. lix. figs. 6 & 7, mx.]}) ; 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 Caprimidgus they have the same form, are 

 much like those of the " Dendrocolaptidse " and " FormicariidEe," 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 &fox than of an ox; and its sharp outstretched ears are formed by the extension 

 of bony matter into the in turned alinasal lamina (^. al) ; 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, ?;, e.pa). 



In old birds the septum nasi, which is well notched ofl' from the far- projecting eth- 

 moid, becomes bony above, the alinasal and inferior turbinals become largely calcified, 

 but the alee 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 fii'st summer. 



With one exception in these examples, namely Menura, the Coracomorphse 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 I'odargus 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 o\'er- 

 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. pi. 21. fig. 8) the pars plana, 



