THE SALIVARY GLANDS IN ANIMALS. 581 



the hard-shelled Echinodermata, a singular masticatory apparatus is found, 

 which, in its perfect form, consists of five large flattened, calcified denticles, 

 having their free edges surrounding the oral aperture ; the outer borders of 

 these denticles, very peculiar in form, are received into a framework, the 

 whole structure, in its entire state, forming the lantern of Aristotle ; power- 

 ful muscles act upon these denticles, which comminute, or triturate, the food. 

 No denticles exist in the Coelenterata ; minute denticular organs are seen 

 in some of the stomatode Infusoria, but they are, of course, absent in the 

 astomatous Protozoa. 



The Salivary G-lands, and Insalivation, in Animals. 



Salivary glands, or glands opening into the mouth, exist in most animals. 

 In the Mammalia, they are nearly always present, but differ much in number 

 and size. In the higher Mammalia, they resemble the glands in Man, except 

 that the submaxillary is unusually large, and, in the seals and cats, the sub- 

 lingual gland appears to be wanting. In Herbivorous, the salivary glands 

 are larger than in Carnivorous Mammalia, in harmony with the more bulky, 

 often drier, and amylaceous character of the food. In the Ruminants, all the 

 glands, but especially the parotids, are very large, and even supernumerary 

 glands are found, as in the ox. In the ant-eater, the salivary apparatus is 

 enormously developed ; the glands cover the forepart of the neck, and, even 

 reach to the chest ; a special reservoir, or salivary bladder, exists beneath the 

 mouth, in which the saliva is probably detained ; when rendered viscid, by 

 absorption of its fluid, it lubricates the tongue, and assists in catching ants. 

 In the Cetacea generally, the salivary, like the lachrymal, glands are wanting, 

 the fluid medium in which they live, and the animal nature of their diet, ren- 

 dering saliva unnecessary ; in the herbivorous dugong, however, the parotid 

 glands exist, but not the sublingual. 



In Birds, the salivary glands are small in the wading and web-footed spe- 

 cies, which live upon soft animal food ; whilst they are proportionally larger 

 in the rapacious and granivorous species. The saliva of birds is chiefly used 

 to lubricate their food. In the woodpeckers, these glands are large, and the 

 viscid saliva assists the tongue in entangling insects. In the Chinese swal- 

 low, which builds the edible nests, the parotid gland is largely developed, and 

 its secretion is used in making the nests. 



Amongst Reptiles, large salivary or buccal glands, found in the Ophidia 

 generally, but not in all species, beneath the gum, along the margins of both 

 jaws, serve to lubricate their prey before it is swallowed. The poison-glands 

 of the venomous species may perhaps be regarded as extraordinarily modified 

 salivary or buccal glands. In the Chelonian and Saurian reptiles, the salivary 

 apparatus consists chiefly of lingual glands. In the chameleon, these are 

 found in the enlarged extremity of its singularly formed insect-catching 

 tongue, and secrete the slimy mucus with which it is covered. 



In the Amphibia, similar glands are found, which, in the toad, serve a like 

 office. 



In Fishes, no salivary glands exist. 



In the Mollusca, glands opening into the mouth, or into the commencement 

 of the gullet, and therefore presumably salivary, exist in nearly all Cephalo- 

 pods, Pteropods, and Gasteropods, varying in form and size, according to the 

 construction of the mouth, and the nature of the food. 



Amongst the Annulosa, glands, always regarded as salivary, exist in well- 

 marked, but most variable forms, sometimes opening into the mouth, at the 

 base of the mandibles, or beneath the proboscis, and sometimes further down 

 near the stomach. These glands are, of course, minute and simple in struc- 

 ture, forming either short follicles, vesicles, blunt-ended tubes, long twisted 

 tubes, as in all butterflies, and most beetles, or even branched tubes, as in 

 Blaps. In the Myriapods, similar glands exist. In the Cirrhopods, they are 

 of considerable size, and form the cement gland. 



In the Annuloid Echinodermata, elongated caecal tubes surround the o?so- 

 phagus, and secrete a viscid fluid, which mixes with the food. Salivary tu- 



