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The back of the mouth, in Ruminants, presents its chief modifications in the Camel-tribe. A broad pendulous flap hangs down from the fore part of the soft palate and usually rests upon the dorsum of the tongue. The velum palati extends beyond this process, some way down the pharynx and terminates by a concave border. The pharynx behind the velum dilates into a sac. In the rutting male the palatal flap is greatly enlarged. I have found it extending ten inches down the pharynx, passing below the margin of the soft palate and the opening of the larynx, into the œsophagus: in the living animal it is, at this season, occasionally protruded, with a belching noise, from the mouth. Its surface shows the pores of innumerable mucous crypts, and in the ordinary state, in both sexes, the flap may apply its own secretion, and water regurgitated from the storage-cells of the stomach, to the extended surface of the pharynx and root of the tongue, so as to allay the feeling of thirst and help the animal to endure the long remissions of drinking to which it is liable in traversing the desert.

The mouth in Carnivora is characterised by the width of its gape, and the mobility, dilatability, and contractility of its muscular and membranous walls. Cheek-pouches have not been found in any species. The great extent of faucial membrane between the back of the tongue and the larynx, with the coextensive soft palate in the Lion and some other large Felines, has been adverted to (p. 198); also the retroverted spines, and the lytta of the tongue in connection with the work of the mouth, in certain Carnivora. In the Hyæna the tonsils are relatively larger than in the Lion. The palatal gum is transversely ridged in most Carnivora. The provision for the lubricating mucus at the back of the mouth and fauces is much less in the present than in the hoofed group of Mammals.

In Quadrumana the Cercopitheci, Macaci, and Cynocephali have cheek-pouches, the slit-like orifices of which are a little within the labial commissure; the cavity extends outside and below the mandibular rami, where it is occasionally seen much distended with food. The Semnopitheci and Colobi, remarkable for their large sacculated stomachs, have not such cheek-pouches : they are wanting also in Lemuridæ, Platyrhines, and tailless Apes.

The Lemurida have the palatal gum ridged. In the Aye-aye' there are three curved transverse ridges anteriorly, convex forward, followed by four transverse pairs of similar ridges. In other Lemurida the palatal ridges are similarly curved, but cu'. p. 41, pl. xii, fig. 6.

usually undivided, from five (Potto) to eight or nine (Galago) in number between the two anterior ridges are the orifices of canals leading from the palate to the nose.

The uvula is represented in the Aye-aye and some other Lemuride by a medial longitudinal fold from the back of the soft palate close to the margin, but does not project so as to divide the fauces into two arches: this form of soft palate begins to appear in Platyrhines: in the Baboons the uvula is thick and short: in the Apes it approaches nearer the proportions of that appendage in Man.

In the higher Quadrumana the palate is smooth, or unridged, as in Man.

§ 224. Salivary Glands.-Fluids of different properties are poured into the mouth in aid of its various functions of receiving, retaining, comminuting, softening or dissolving, tasting, and transmitting throatward, the food. For the preparation of these fluids corresponding modifications of glandular parts exist, from the simple mucous follicle to aggregates of three or of more complex follicles, with further multiplication and compaction of secerning surfaces, in groups and bodies, forming glands and ducts with definite names.

As the function of the mouth is simplified so is the condition of such ministering glands. In the piscivorous Cetacea, which bolt their food like fishes, the parotids and submaxillaries are not present the latter are represented with the sublinguals, in a diffused form in whalebone whales. The parotids are large in Sirenia; their ducts open in the Manatee on two papillæ, one on each side the fore part of the palate: in the Dugong the parotids are situated immediately behind the ascending mandibular rami: there is a thick layer of mucous glands above the membrane covering the hard palate.

In the Ornithorhynchus the parotid, fig. 3, E, is divided into flat portions or lobes thinly applied to the fundus of the cheekpouch and anterior to the long meatus auditorius. The submaxillary, ib. D, is a moderately-sized, oval, compact body, situated behind and below the meatus auditorius. The duct passes under the omo-mylo-hyoideus, ib. 10, and then, contrary to the usual mode, begins to be disposed in a series of about twelve close transverse folds, and terminates by a simple aperture at the frænum linguæ. In the Echidna the submaxillary gland, fig. 302, b, is of unusual dimensions: it extends from the meatus audi

1 CXVII". p. 29.

torius along the neck, and upon the anterior part of the thorax: it is a broad, flat, oblong lobulated body, narrowest at its anterior extremity, from which the wide duct emerges. When the duct

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has reached the interspace of the lower jaw, it dilates, and then divides into eight or ten undulating branches, which subdivide and ultimately terminate by numerous orifices upon the mem

branous floor of the mouth. This modification of Wharton's duct' appears to be unique. The large size of the glands and the mode in which the secretion is spread over the floor of the mouth relate to the lubrification of the long, slender, and extensible tongue, and to its fitness as an instrument for obtaining the insect food of the spiny Monotreme.

The salivary glands in the carnivorous Dasyures consist of a small parotid and a large submaxillary gland on each side. They do not agree with the dogs in having the zygomatic glands. The submaxillary is placed in front of the neck, so that its duct passes on the dermal side of the tendon of the biventer maxillæ, and terminates half an inch from the symphysis menti. There is a thick row of labial glands along the lower lip. The Opossums and Bandicoots present a similar salivary system. In the Phalangista vulpina there is a sublingual gland on each side of a firm texture, about one inch in length and three lines broad; a roundish submaxillary gland about the size of a hazel-nut; and a broad and flat parotid, larger than in the entomophagous or sarcophagous Marsupials. The parotid glands are relatively larger in the Koala, in which the duct takes the usual course over the masseter and enters the mouth opposite the third true molar, counting backwards. In the Wombat I found the parotid glands very thin, situated upon both the outer and inner side of the broad posterior portion of the lower jaw; the duct passed directly upwards and outwards to the insertion of the sterno-cleido-mastoideus; here it was buried in the cellular substance anterior to that muscle, then turned over the ramus of the jaw, and, pursuing a somewhat tortuous course over the masseter, entered the mouth just anterior to the edge of the buccinator. The submaxillary glands were each about the size of a walnut; their ducts terminated as usual on each side of the frænum linguæ. In the great Kangaroo the parotid is very large, extending from below the auditory meatus three or four inches down the neck: In the Potoroos it reaches as far as the clavicle. In both genera this gland is separated from the submaxillary gland by the submaxillary vein. The sublingual glands are elongate, but of moderate size. The tonsils are small in all the Marsupials, but are not represented in the carnivorous species, as in the placental Feræ, by simple glandular pouches at the sides of the fauces; for example, they consist of an oblong glandular body on each side in the Dasyurus macrurus.

In Rodents, as in Marsupials, the proportions of the parotid and submaxillary differ according to the nature of the food. In the

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omnivorous rats with ferine tendencies, the submaxillaries are in excess in most other Rodents which subsist mainly or exclusively on vegetable products the parotids are the largest. They are enormous in the Beaver, extending from before the ears forward and downward to contact with the submaxillaries, which are about one-twentieth their size; the whole forming a sort of glandular collar: the buccal glands are numerous. In Leporida the parotids partly inclose the base of the ear-conch and also descend to meet the submaxillaries: the parotid duct crosses the upper part of the masseter and terminates opposite the last upper molar tooth. The submaxillary duct terminates at the side of the frænum linguæ: the submaxillaries are thin and long: the chief mass of the molar follicles is near the upper molars. The submaxillary glands are almost as large as the parotids in the Paca (Cœlogenys): both glands are large the latter present a compact reddish tissue. There is also a large zygomatic salivary gland, which exists, of smaller relative dimensions, in the Guinea-pig (Aperea). In the Hamster the parotids are elongate, narrow, and applied, as in the Ornithorhynchus, to the back of the cheek-pouches: there is also an accessory lobe, beneath the masseter. The submaxillaries are large, round, and of a reddish colour. The sublinguals are small, subglobular. In Bathyergus the salivary glands are smaller than in most other Rodents.

Amongst Insectivora the hedgehog is remarkable for a zygomatic gland which seems to be a development of the homologue of the molar' glands in Marsupials. The parotids are larger than the submaxillaries; but both are well-developed. The sublingual follicles are in two series, the larger one next the mandibular ramus. The mole has large parotids and submaxillaries, the former oblong, the latter subdivided into roundish masses: the sublingual is placed very near the mandible: there is no zygomatic gland. In shrews the maxillary exceeds the parotid gland in size: the latter follows the auditory meatus in its inferior position. The same proportions hold in the insectivorous bats: but in the fruit-eating Pteropines the parotids are the larger glands.

Great is the diversity of the salivary system in the order Bruta, as the difference of food and ways of getting it might indicate. The parotids are somewhat less than the submaxillaries even in the phyllophagous Sloths, and are much the smallest in the insectivorous families. In the Armadillos the parotid gland is small : its duct opens into the mouth near the angle of the lips. The

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