filled up by even the bony growths; -it remains as the
" median occipital fontanelle."The vomer in this group is of great interest, being ex tremely variable, and often having a supplementary bone attached. It is azygous. The palatines also, which have rounded posterior angles and double keels, often have a medio-palatine where they unite, and also receive the meso-pterygoid spur. In some types, as Gyps fulvus, the large rounded palatine flap is partly severed off as a " transpalatine." Where the ascending laminae of the palatines meet below the sphenoidal rostrum, there a bony deposit takes place; this, if truly azygous, is a medio- palatine ; if oblique, it is one of the meso-pterygoids, which, in the Rapaces, get between the palatines, coalesce - with each other, and form a keystone, as in Ulula stridula. In others, as the young of Falco tinnunculus and the adult lldotarsus ecaudatus, there is one small, obliquely-placed ossicle in the front of the palatine suture. In Neophron percnop erus there is one free meso-pterygoid attached to the right hinder fork of the vomer. In Dirholophus cristatus there is a large medio-palatine wedged in in front, and to it the cultrate, fenestrate, and pedate vomer is attached. In the Falcons the vomer is pedate, and, in the larger kinds, fenestrate. In Ulula stridula there is a small vomer attached to a small medio-palatine, and having over it an equally small median septo-maxillary. The latter bone is large in Asia otits, and small in Neophron percnopterus, Circus cyaneus, and Haliastur indus. The vomer is most aborted in the Eagles and Vultures (often absent) ; but it is long in Neophron. We have found a small bony wedge (oblique meso-pterygoid) in Sarcorhampkus papa. Professor Huxley s figure of the skull of Gypogeranus is deficient in not showing a small vomer (fig. 24, p. 442). A specimen sent to him by the writer (after the paper appeared) has this little bone distinct. The frowning brow is obtained in these birds by a huge super-orbital process of the lachrymal in Dicholophus, Gyps, and Falco. In many kinds (Hawks, &c.) there is a distinct super- orbital at its extremity. The eyeball, with its massive bony rim, is quite equal in Dicholophus to that of the diurnal Rapaces generally. Its hyoid also is thoroughly Raptorial. Its glossal (double) piece is spatulate, and, like that of its congeners, approaches the glosso-hyal of the Parrots in breadth. Unlike its congeners, the Cariama has its nasal septum but little ossified ; and it possesses an " os uncinatum," propping up the pars plana, as in the Gull, Albatross, and many other birds.
A description of the palate of the Sparrow-Hawk (Accipiter nisus, will illustrate that of Raptorial birds generally, and also the meaning of the term desmognathous.[1] The speci men figured (fig. 25) was a half-developed nestling. Its round occipital condyle, and the various foramina (8, 9), are shown in the occipital region, and outside and above this arch are seen the hinder face of the opisthotic (op.}, and in front of the tympanic ala of the exoccipital (e.o.) there is an uncinate bone in relation with the prootic, opisthotic, squamosal, and exoccipital, where they all meet together. This is the "pterotic" (pto.), a huge bone in Osseous Fishes, and walling-in much of the labyrinth. In Serpents only a film of ectosteal bone represents it, and in Lizards such a plate appears, overlapping cartilage which has begun to calcify. It develops and becomes part of the parotic process. The basi-temporal plate (b.t.), the rostrum, with its arrested basi-pterygoids (b.pg.), are shown, and on each side the double condyle of the quadrate (q.), characteristically placed transversely. The zygoma, is composed of thin needles of bone (q.j., j.) ; the zygomatic process of the maxillary is, behind, bound up with the jugal and quadrato-jugal, and in front passes into the upper dentary region, half overlapped by the dentary process of the premaxillary (px.} The dentary edge of the maxillary sends inwards the maxillo-palatine plate (mx.p.), which meets its fellow at the mid-line, and also grows retrally and superiorly into an elegant shell-like mass.
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FIG. 25. Skull of nestling $pan-mc-H,iick (Accipiter nisus), palatal view, X 2
diameters. The circular space on each side of the basi-temporal (ii.t.) is the opening of the anterior tympanic recess. The meso-pterygoids (m.pg.) show part of their lower face on the post-palatine region ; the basi-pterygoids (b.pg.) are mere knobs, and the common eustachian opening is seen between them. The maxillo-palatine plates (mx.p.) are dotted to show their spongy character.
The right and left plates lie edge to edge, as in the adult Cariama, and are imperfectly direct in their desmo- gnathism. The palatine processes of the premaxillaries bind the fore-ends of the palatines, which in turn bind under the maxillo-palatine plates. The gap in front is filled with the fast ossifying septum nasi ; it is pedate in front, and behind sends out a process on each side ; these spurs ankylose afterwards with the maxillo-palatine plates, and they with each other. The palatine bones (pa.), strap- like, widen backwards, and then gently narrow to the end, leaving no sharp postero-external angle. The wedge of bone which has been fretted off from the fore-end of each of the rod-like pterygoids (py.) binds on the postero- superior edge of each palatine, and the inner plate of these bones covering the under surface of the sphenoidal rostrum imperfectly, allows part of these bony wedges the " meso- pterygoids " (m. pg.) to be seen from below. The bird has all thzperiotic bony centres, viz., five, as in Osseous Fishes ; it has distinct cartilaginous orbital alrc, which are, like the presphenoid, separately ossified, besides an azygous ossification in membrane belonging to the same category.
of Desmoynathce is as remarkable as the variability of the last, and yet it is potent in genera and species. " The rostrum (see op. cit., p. 465) is arched and hooked at the extremity, and is regularly articulated with the frontal region of the skull." Therefore we find that the cranio facial cleft is complete a state of things not often occur ring. The development of this type has not been observed,
yet we can interpret the metamorphic results by othe?- ↑ See Monthly Microscopical Journal, Feb. 7, 1873, p. 45, plate 5,
- !. 2. A paper by the same writer in the Linnean Transactions,
