through the Roebuck, Fallow-deer, Red-deer, to the Ox, where it constitutes the broad naked muzzle.'

The organ of smell in Carnivora mainly differs from that of hoofed Herbivora in the greater relative size and strength of the ethmoturbinal, the shorter, deeper, more massive and much more subdivided maxilloturbinal.' In the Lion the ethmoturbinal is of a pyramidal form, its broad base continued from the short labyrinthic part attached to the cribriform plate, its apex terminating forward, between the naso- and maxillo-turbinal. The mesial surface of the ethmoturbinal shows numerous furrows, two of which are longitudinal and parallel with the upper margin of the bone, the others radiating from the lower part of the attached base the lateral or outer surface is less complex and extensive; but, on removing the outer layer, a series of concentric curved folds are exposed. The nasoturbinal,' holding as in Ungulates the highest position, is an elongate cone, coextensive with the roof of the nasal cavity and with its base opposite to the frontal sinus: the mesial surface shows a series of deep arched folds; the lateral one seems more even, but when the peripheral lamella is removed a series of longitudinal folds of the bone is brought into view, beneath which are concentric folds arched or curved in the opposite direction to those in the ethmoturbinal. The maxilloturbinal is fusiform; the hind end is attached to the outer wall of the nasal chamber below the middle of the nasoturbinal; whence the bone rises and expands, crossing the anterior end of the ethmoturbinal, and again diminishing to its anterior and upper attachment behind the external bony nostril. From its position, therefore, the odorous atoms, in inspiration, must first impinge upon this bone, and the pituitary membrane is thicker and more vascular than on the other turbinals. Its mesial or septal surface presents one curved groove, parallel with and near to the lower margin of the bone: the outer surface has a like character. The more glandular part of the pituitary membrane is at the fore part of the floor of the nasal chamber, not occupying so deep a fossa as in Ungulates.

The sources and distribution of the nervous supply corresponds with that noted in the Giraffe: the septal branches of the olfactory curve down toward the thickened base of the partition. In the Dog, the longitudinal folds of the labyrinth' are about four, fewer in number but larger than in the Sheep: the athmoturbinal is continued from the undermost and curves upward slightly to This was pointed out to me by the estimable and justly famed water-colour artist and animal painter, Robert Hills, F.L.S.

the nasoturbinal as it advances: the maxilloturbinal is shorter, relatively broader and deeper, and much more extensively folded than in the Lion. This is the part of the olfactory organ that reaches the extreme of turbinal development in the Seal-tribe. In the large species dissected for the preparation, No. 1557, the maxilloturbinal is attached by its contracted extremities, the intervening enormously swollen mass is divided by a deep longitudinal furrow into two parts; the free surface of which is singularly complicated by folds, radiating from both extremities of the bone and subdividing dichotomously.' These turbinals seem to block up the entry of the nasal respiratory passages, and must warm the air in arctic latitudes as well as arrest every indication from the effluvia of alimentary substances or prey. The nasoturbinals, in some Otaria, extend backward, with the nasal chamber, above the long rhinencephalic compartment of the cranium.

:

2

In the Quadrumana the nasal chamber loses length and gains, but in less proportion, depth and breadth, from the Lemurs up to the Apes: the maxilloturbinal ceases to be suspended by its extremities, and acquires a linear longitudinal attachment externally to a ridge on the maxillary wall of the nasal chamber. This turbinal is divided into two chief parts lengthwise, in Lemurida, where it is longest the nostrils are here terminal, the anterior expansion of the septal cartilage curves outward and downward on each side, and, with a corresponding degree of curvation of the principal alar cartilage, gives a subconvolute form of nostril to most Strepsirhines. In the Aye-aye they describe a semicircle; and the nasal chamber by its shortness, depth, and predominance of the ethmo- over the maxillo-turbinals exemplifies the quadrumanous affinities of the species. In Platyrhine monkeys, the septal cartilage is remarkable for the transverse extent of its anterior terminal expansion between the nostrils, pushing them and their alar cartilages outward. In Catarrhines this expansion is much reduced; and the nostrils are obliquely approximated. In both groups the nostrils cease to be terminal; in a Bornean Douc (Semnopithecus nasicus), the nostrils are produced upon an ill-shapen prominent subcylindrical In the Gorilla each nostril is surmounted by a broad prominence, arching outward from a lower part impressed by a median furrow; a deeper indent divides the nasal ala from the cheek: the aspect of the nostrils is forward and a little outward. The septal cartilage extends to the tip of the interalar prominence. 2 cu. p. 18, pl. viii. fig. 6.

nose.

1 xx. vol. iii. p. 100.

In Man the number of olfactory nerves varies from fifteen to twenty after traversing the cribriform plate, they divide into two chief sets, septal' and turbinal,' and ramify between the periosteum and the pituitary membrane before terminating on the latter. The septal nerves, fig. 158, a, are about twelve in number, are quickly resolved into brushes

of filaments, which unite together to form plexuses, and send off branches forming

158

159

finer plexuses, traceable to near the base of the septum. The posterior fourth of the septal membrane is chiefly supplied by the nasopalatine nerve, b. The turbinal' or labyrinthic olfactory nerves are more numerous, rather smaller, and more plainly anastomotic in their course over the upper and middle turbinals, lying in grooves of the former, and extended chiefly upon the inner and lower front of the midturbinal; a few combine with that part of the nasopalatine which supplies the lower part of the middle turbinal. The lower turbinal is almost exclusively supplied by a branch of the nasopalatine.' The main characteristic of the human organ of smell is the prominence of the fore-part of the chamber, having the nostrils on its lower surface, and constituting the feature emphatically called the nose,' figs. 159, 161. The formative fold of integument is supported by eleven cartilages, of which one is medial, the others lateral, in five pairs. The medial or 'septal' cartilage, fig. 160, is usually triangular, with three unequally curved margins: the upper one,

a, is fixed in the groove of the perpendicular plate of the ethmoid,' the lower border, b, fits into the front groove of the

races.

vomer; the anterior border, c, extends from the nasal bones, where it is thickest, as at 2, d, and grows thinner down toward the apex of the nose. The varying proportions and form of the septal cartilage mainly govern the shape and prominence of the nose: it is least developed but thickest in the Negro and Papuan

The lateral cartilages vary in size and shape, the upper one, fig. 159, a, is triangular, continuous in front with its fellow,

161

where they are closely connected with the upper half of the anterior border, fig. 160, c, of the septal cartilage. The largest of the alar' or pinnate cartilages, fig. 159, b, is bent upon itself, almost surrounding and governing the shape of the nostril: it is movably connected with the lower and outer part of a. To the outer and hinder apex of the cartilage b, is joined the first of the three small cartilages, c, d, e, which support the posterior convex part of the

ala' or wing of the nose. The flexible fibrous tissue connecting these elastic cartilages allow of the movements of the parts to be readily produced, and the muscles are accordingly feeble. The pyramidalis nasi,' fig. 161, c, is continued from the medial portion of the frontalis,' fig. 28, f, which descends over the upper part of the nose to the cellular tissue covering the cartilage, a, and thence onward to combine. with fibres of the 'triangularis nasi,' fig. 161, e, and fig. 29, n. The levator labii superioris alæque nasi' is shown at dd, fig. 161; in the degree in which the alar is distinct from the labial portion, or has been distinctly exercised, the wings of the nose can be ex

panded independently of any other movement of the face. The 'depressor alæ nasi,' ib. f, arises from the outer border of the sockets of the canine and contiguous incisor: the fibres ascend to the ala, many of them arching over the outer and back prominence of the nostril. The depressor septi,' ib. k, is detached from the upper part of the orbicularis oris,' fig. 29, oo, the fibres converging from each side toward the nasal septum. The small triangular patch of pale fibres, fig. 161, g, is the compressor narium minor:' the larger quadrilateral muscle, h, is the levator alæ proprius.' In races, like the Mincopies of the Andaman Islands who scent the ripeness of indigenous fruits, moving the thick alæ of their squab nose, as they explore their dark forests for this purpose, the nasal muscles may be expected to be well and instructively developed.

162

§ 216. Organ of Hearing.-The advance in this sense-organ in the mammalian class is seen in the extension of the cochlea, fig. 162, f, into coils suggesting the name; in the greater proportion of the perilymph; in the ossification of the cartilages between the stapes and tympanum forming the malleus,' and commonly also the incus;' and in the presence, save in most swimmers and burrowers, of an external ear or conch, served by muscles for various movements to catch the sound. Besides the cochlea, the labyrinth, fig. 162, includes, as in other Vertebrates, the semicircular canals, c, d, e, and the intermediate space or vestibule,' a, by which they now communicate with the cochlea. The semicircular canals form a smaller proportion of the labyrinth in Mammals than in lower Vertebrates; they retain, however, their posterior position to the vestibule and cochlea.

Osseous labyrinth of the left side. Human, nat size.

The larger opening in the bony wall of the labyrinth is called, from its shape in Man, the foramen ovale,' or, from its situation in the labyrinth, 'fenestra vestibuli,' fig. 162, a: it is closed by the base of the stapes. A smaller round aperture,' ib. b, is called 'fenestra cochleæ,' because it forms the terminal orifice by which one of the turns of that part, scala tympani,' would open into the tympanum, were it not naturally closed by membrane.

A depression in the petrosal or bony case of the labyrinth receives the facial and acoustic nerves, and terminates in a cul-desac, one division of which gives passage to the facial, fig. 165, k; the others receive divisions of the acoustic nerve, and transmit