naturally subsist. The Cheek-Teeth in the lower jaw of man, like those of herbivorous and frugivorous animals, are simply raised into rounded elevations; and are directly opposed to those of the upper jaw, so as to mash and grind the substances that come between them; but in carnivorous animals they shut within those of the upper jaw, so as to tear and cut the flesh on which they feed, preparatory to its being swallowed: when both series are viewed together, the general outline may be compared to the teeth of a saw, and their action to that of a pair of shears.

ARTICULATION OF THE LOWER JAW.

63. All lateral motion of the lower jaw in the Carnivora, is not only prevented by the structure of the teeth, and the closing of the lower cheek-teeth within those of the upper; but is also rendered quite impossible by the rising edges of the glenoid cavity; so that the articulation, or joint, admits of the opening and closing motion only; thus rendering it more secure under the extreme muscular action to which it is frequently subjected. In herbivorous animals, the condyle is adapted to, and works upon, a wide and somewhat convex surface; and, consequently, the articulation allows considerable lateral motion, for masticating the vegetable matter on which they feed. Great freedom of lateral motion, is also possessed by the human inferior maxilla; so that the food can be completely triturated by the grinding surfaces of the molars,

before it is swallowed;-a character evidently connecting man with the Herbivora and with the Quadrumana, which possess a similar articulation.

ZYGOMATIC ARCH; TEMPORAL AND MASSETER MUSCLES.

64. The temporal and masseter muscles, by which the motion of the lower jaw is effected, are of immense size in carnivorous animals. The temporal muscle occupies the whole side of the skull, and fills the space beneath the zygomatic arch, the span and spring of which are generally an index of the volume of this muscle; while the extent and strength of the arch, indicate the development of the masseter muscle. On the contrary, the pterygoid muscles, which aid the lateral movement of the jaw, are extremely small. The Zygoma is of great size and strength in the Carnivora;—consisting of a long process of the masseter bone, overlaid by the usual process of the temporal bone, which is equally strong. The arch extends not only backward but upward,-by the bending down of the extremity;-the line of anterior declination falling precisely on the centre of the carnassière tooth;the point in which the force of the jaws is concentrated, and where it is most required for cutting, tearing, and crushing their food. In Ruminants, the zygomatic arch is short, and the temporal muscles are small; but the masseter muscle on each side extends beyond the arch, and is attached to the greater part of the side of the maxillary bone. The pterygoid fossa is ample, and its

muscles are largely developed. The arch is small in man, the temporal muscles moderate, and the force of the jaws comparatively weak.

SALIVARY GLANDS.

65. The food of all animals possessing the true molar teeth, requires due mastication, and mixture with the saliva, before it is passed from the mouth into the œsophagus; and, for the secretion of this fluid, salivary glands are present in almost all animals, except the cetacea and fishes. In insects, they have the character of prolonged cœca; and are very feebly developed in the amphibious Mammalia. They are numerous and large in those animals living on food which requires continued mastication,—as in Ruminants; and they are so situated, that the play of the muscles, in the act of chewing, communicates to them a proportionate stimulus. In the Carnivora, the food of which requires little or no mastication, these glands are very small; and, consequently, the saliva is very limited in quantity. The salivary glands are not proportionably so large in man as in herbivorous animals, nor so small as in the Carnivora. It is also stated, that these glands are much more developed in those of our race, who have long subsisted on vegetable food, than in those who have lived chiefly on animal food. The secretion from these glands, in man, is very copious; which indicates his much nearer alliance to herbivorous, than to carnivorous animals.

ALIMENTARY CANAL.

66. The length, divisions, structure, and capacity of the alimentary canal, assist us still further in determining the dietetic character of man. In carnivorous animalswhether among the Mammalia, birds, reptiles, fishes, or insects—it is generally short, its structure simple, and its capacity small; whereas, in herbivorous animals, the canal is considerably longer in proportion to the size of the animal; and the stomach, colon, and cæcum, are much more complicated.

67. The length of the intestinal canal, as compared with the length of the body, is, in carnivorous animals, as three, five, or (in some few cases) eight to one. Herbivorous animals vary considerably in this respect: in the Pachydermata (as the horse, ass, &c.) the proportion is six, eight, or eleven to one; in Ruminants (as the ox, deer, sheep, &c.) it is eleven and even twenty-eight to one; and in the Simiæ, six or eight to one. In man, the proportion has usually been considered about six or seven to one; but-as the legs and thighs were improperly included in estimating the proportion in his case, and excluded in that of other animals-the result is incorrect; and we may regard ten or twelve to one, as a nearer approximation to the truth. In the hog the proportion is thirteen to one. Length, alone, however, is an imperfect criterion; and, unless the diameter and complication of each division of the canal be taken into consideration,

our inferences respecting the natural food of an animal may be incorrect. The hyena, for instance,-which lives on the flesh and bones of other animals, has an alimentary canal about eight times the length of its body; while the porpoise and dolphin, which feed on fish, have a canal extremely long, but simple in its structure.

STOMACH.

68. The stomach of the Mammalia varies very much in form and complexity; but even this important organ is not sufficient of itself to indicate the true dietetic character of an animal, without reference also to the cæcum, colon, and length of the whole canal. The stomach of carnivorous animals generally consists of a simple, globular sac, without internal division; and the same form is found in many insectivorous animals. Their food being highly concentrated, and differing little from the nature of their own tissues, requires but a slight change to prepare it for assimilation; and its liability to become putrescent, requires for it a quick passage through the canal. In the Herbivora, subsisting on far less concentrated food, the stomach is divided into two or more compartments; and in the Ruminants it is very large and complicated,— consisting of various cavities. Some animals of this class, as well as others that are frugivorous, have a stomach comparatively simple,—differing little from that of a carnivorous animal; as is the case with the horse : in all such instances, however, the cæcum and colon are