The salivary glands are present in all the Cephalopoda, with the exception of Loligo psis. In the Onychoteuthis two glands are situated at the root of the tongue. They are in general, however, four in number, two at the root of the tongue, which give off distinct ducts which terminate at the commencement of the cesophagus ; the other pair, generally longer than the superior, is lodged in the vis ceral sac, on each side of the upper part of the crop. The ducts of the last form a single tube which opens in the neighbourhood of the spiny portion of the tongue.
The salivary glands are absent in Pisces.
Among reptiles in the Chelonian, Saurian, and Batrachian orders, the substance of the tongue seems principally made up of a glan dular mass formed by a multitude of little tubes united at their bases, but becoming se parate towards the surface of the tongue. In the Ophidian reptiles two glandular organs placed immediately beneath the skin of the gums surround the margins of the upper and lower jaw, and pour an abundant salivary secretion into the mouth. (Rymer Jones.) In many genera the salivary apparatus is de ficient. The poison glands of serpents can hardly be reckoned among the salivary organs, being destined for a special secretion, and forming the analogues to similar glandg in the Arachnida.
In Ave: the salivary glands present con siderable variation in their number, position, and degree of development. In the crow the only indication of a salivary apparatus is a series of simple cone-shaped follicles, placed along the sides of the oral cavity, upon the rnucous membrane of which they open by distinct orifices. In general, however, there are four pairs, two sublingual on each side beneath the tongue, two maxillary, divided each into an anterior and posterior, and opening by special ducts in front of the tongue, and a gland which can be compared to the parotid. These are generally all present in the Rapaces, Pas seres, and Gallimm ; and appear to be absent in Sula, Carbo, and Phmnicopterus, and but slightly developed in the Grallce and Palmi pedes generally. In the goose they occupy the entire space included between the rami of the lower jaw, being closely united in the median line, and opening into the mouth on each side of this by a series of orifices. In the watercoot and Hirundo esculenta, the parotid is highly developed, in the latter the secretion serving for the preparation of its edible nests. In the woodpecker the glan dular mass is of extraordinary size, extending from the angle to the symphysis of the jaw on each side, and opening by the confluence of the two ducts into a single orifice at the apex of the mouth.
In Illanznzalia the salivary glands present considerable variation. In the Monotremata they are partially deficient : in the Echidna there appears to be no parotid ; the submax Diary, on the other hand, is highly developed, extending from the meatus auditorius along the neck, and upon the anterior part of the thorax. Its ducts terminate by numerous
orifices on the membranous floor of the mouth, and pour out a secretion for the lubrification of its long and slender tongue. In the Cetacea the salivary. glands are absent. In the Dugong, however, one of the herbivo rous Cetacea, the parotids are highly deve loped. In the Ruminantia the three pairs are highly developed, particularly the parotid ; and in addition to these there is a group, apparently continuous with the molar, which mounts up along the superior maxillary bone, beneath the zygonia, to the globe of the eye, as observed in the ox, the sheep, and the horse. The excretory ducts pierce the mu cous membrane near the posterior margin of the superior alveolar ridge.
In the armadillo, among the Edentata, the submaxillary gland has appended a reservoir or bladder, receiving the saliva by small ducts, which open into it posteriorly in a valvular manner. A single duct comes off from its anterior part, and terminates just behind the symphysis of the lower jaw. The saliva is very tenacious, the serous part being pro bably absorbed during its detention in the reservoir, and is expelled at the extremity of the mouth, in order to lubricate the tongue, which is by this means rendered subservient, as in the ant-eater, to the catching of insects. In the latter animal the salivary secretion takes place from two glands, situated, accord ing to Cuvier, the one in contact below with the upper edge of the masseter, and filling up a great part of the temporal, zygomatic, and orbital foss ; the excretory duct opening into the mouth behind the superior maxilla: the other, probably furnishing the viscid secre tion that coats the tongue in front of the tendon of the masseter, behind the angle of the lips, and then running along the edge of the lower lip as far as the middle. Its canal opens externally at the commissure of the lips.
In the Carnivora the variations of the sali vary glands are but slight. The submaxillary in them, as in the Rodentia and Ruminantia, are large. The sublingual gland is absent in the cat.
The writer of this article has to acknovvledge his obligations to the undermentioned sources, for the preceding account or the comparative anatomy of the salivary glands:— Cuvier, Le cons d'Anatomie comparee ; Owen's Lectures on the Invertebrata; Rymer Jones, General Structure of the Animal Kingdom ; Wagner, Elements of Comparative Anatomy, trans lated by Tulk ; Kelp, De Systeniate Salivali, and the various articles on Comparative Ana tomy in this Cyclopwdia.