. Elements of Comparative Anatomy. 460 COMPAEATIVE ANATOMY. liue^ so that tlie base of the skull is more or less shut off from taking any part in bounding the buccal cavity. The nasal cavities^ which in the Amphibia lead into the buccal cavity at the very anterior edge of the skull, have their internal orifices always placed farther back in the Reptilia, owing to the union of the horizontal processes of the maxillte, palatines, and pterygoids in the middle line, and in front of them. In this way the nasal is more completely shut off from the buccal cavity, and forms an upper cavity, the base o
. Elements of Comparative Anatomy. 460 COMPAEATIVE ANATOMY. liue^ so that tlie base of the skull is more or less shut off from taking any part in bounding the buccal cavity. The nasal cavities^ which in the Amphibia lead into the buccal cavity at the very anterior edge of the skull, have their internal orifices always placed farther back in the Reptilia, owing to the union of the horizontal processes of the maxillte, palatines, and pterygoids in the middle line, and in front of them. In this way the nasal is more completely shut off from the buccal cavity, and forms an upper cavity, the base of which is the roof of the mouth—that is, is the "hard palate/^ These. Kg. 249. Side views of Skulls. -4 Struthio. li Crocodilus. C Python. OJ Ex- occipital. Os Supra-occipital. Pi Pterygoid. Po? Palatine. Tr Transverse. Col Colu- mella, fov Fenestra ovalis. S Foramen for the trigeminal nerve. The other letters as in the preceding figures. changes are least marked in the Saurii, Ophidii, and Aves, more so in the Chelonii, and most completely so in the Crocodilini. The parts that form the suspensorium in Fishes (hyomandibular and symplectic) have undergone just the same fate as in the Amphibia; or, in other words, they have no longer any relation to the cephalic skeleton. The " columella auris " and the jDarts con- nected with it are developed from its rudiments, partly a bony, and partly a cartilaginous skeletal bit which has entered into the service of the auditory organ. When the quadrate is movably united with the skull (Ophidii^. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Gegenbaur, C. (Carl). London : Macmillan
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