. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative; Vertebrates -- Anatomy. OLFACTOEY ORGAX. 175 extends further and further backwards, in correspondence with the PTOwth forwards of the facial region and the formation of O C7 the palate; its posterior part thus comes to lie below the brain and base of the skull. In Crocodiles, as in other Reptiles, there is only a single true turbinal, but externally to it lies a second prominence, which is spoken of as a Each nasal chamber of the Crocodile is divided posteriorly into two superimposed cavities, the upp
. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative; Vertebrates -- Anatomy. OLFACTOEY ORGAX. 175 extends further and further backwards, in correspondence with the PTOwth forwards of the facial region and the formation of O C7 the palate; its posterior part thus comes to lie below the brain and base of the skull. In Crocodiles, as in other Reptiles, there is only a single true turbinal, but externally to it lies a second prominence, which is spoken of as a Each nasal chamber of the Crocodile is divided posteriorly into two superimposed cavities, the upper of which represents the proper olfactory chamber, and is lined by sensory epithelium, while the lower functions as a respiratory portion only. Certain accessory chambers are con- nected with the nasal cavity, which, however, serve only as air- chambers. A large gland, similar to that of Lizards and Snakes, lies in the cavity of the upper jaw, and opens into the nasal cavity. Birds.—In all Birds, as in Lizards, there is an outer chamber, lined by stratified epithelium, and a proper olfactory chamber, which lies above the former. Birds also possess only a single. FIG. 146.—TRANSVERSE SECTION THROUGH THE EIGHT NASAL CAVITY OF A SHRIKE (Lanius minor). OM, J/J/, superior (pseudo) and middle (true) turbinal ; a, upper, and b, lower nasal passage ; LR, air-chamber, which extends into a hollow of the superior turbinal. true turbinal, if by this term is understood a free independent projection into the nasal cavity supported by skeletal parts. Two other prominences (pseudo-turbinals) are, however, present, one of which - lies like the true turbinal in the proper olfactory chamber, while the other, like the pseudo-turbinal of the Crocodile, is situated in the outer portion: these are simply incurved portions of the whole nasal wall (Fig. 146, MM, 031). The form of the true turbinal, which is usually supported by cartilage, more rarely by bone, varies greatly. It is either represen
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