As the nasal bones proceed downward they become somewhat wider. They unite with a long process of the anterior maxillary for the purpose of strength, and then terminate in a singular way. They have their apexes or points on the outer edge of the bone; and these apexes or points are so contrived, that, lying upon, and seemingly losing themselves, on the processes of the anterior maxillary, they complete, superiorly and posteriorly, that elliptical bony opening into the nose which was commenced by the maxillary anteriorly and inferiorly. The nasal cavity of the dog, therefore, and of all carnivorous animals, terminates by a somewhat circular opening, more or less in the form of an ellipse. This bony aperture varies in size in different dogs, and, as we should expect from what we have seen of the adaptation of structure to the situation and wants of the animal, it is largest in those on whom we are most dependent for speed and stoutness. The 'olfactory', or first pair of nerves, have a double origin, namely, from the 'corpus striatum' and the base of the 'corpus callosum'. They are prolongations of the medullary substance of the central portion of the brain. They are the largest of the cerebral nerves. Their course is exceedingly short; and they have not a single anastomosis, in order that the impression made on them may be conveyed undisturbed and perfect to the brain. The olfactory nerve is a prolongation of the substance of the brain, and it abuts upon the cribriform bone, of which mention has been made. I will not speak of the singular cavities which it contains, nor of their function; this belongs to the sensorial system: but its pulpy matter has already been traced to the base of the ethmoid bone, and the under part of the septum, and the superior turbinated bone. Although we soon lose it in the mucous membrane of the nose, there is little doubt that in a more filmy form it is spread over the whole of the cavity, and probably over all the sinuses of the face and head. It is, however, so mingled with the mucous membrane, that no power of the lens has enabled us to follow it so far. It is like the 'portio mollis of the seventh pair, eluding the eye, but existing in sufficient substances for the performance of its important functions.