OSSEOUS SYSTEM OF MAMMALIA. 41 



or less concave, on the under surface, at the root of each zygomatic 

 process of the temporal bone, to which its condyles, or articulating 

 processes, are elaborately adapted : thus, the jaw moves upon the 

 cranium. The extent of motion, depending on modifications of the ar- 

 ticulating surface, which the lower jaw possesses, differs materially in 

 different tribes of Mammalia ; but ever harmonizes with the structure 

 of the teeth ; and, consequently, has reference to the nature of the food, 

 and the general economy of the species. Hence, let the comparative 

 anatomist examine only the characters presented by this articulation, and 

 he will be able to sketch a broad outline of the habits and manners of 

 the animal. In some, as, for example, the Ox and Sheep, a free lateral 

 motion of the lower jaw being necessary, its condyle is adapted to, 

 and works upon, a wide, and even somewhat convex surface : in others, 

 the condyle is tightly fitted into a deep concavity, with an elevated 

 rim before and behind, which prevents the slightest movement of the 

 jaw from side to side, restricting its action to a mere scissor-like open- 

 ing and shutting : such is the case in the ferocious Carnivora. In others, 

 again, there is an intermediate state of freedom : but, on this part of the 

 subject, there will be occasion to enlarge hereafter. 



Within the recess formed, as described, by the bones of the jaws and 

 of the palate, is seated the tongue, the chief organ of taste, abundantly 

 supplied with gustatory nerves : it serves, besides, by its muscular action 

 and sense of feeling, to direct the food between the teeth ; and, after 

 mastication, to propel it, by pressure against the palate, into the fauces, 

 or back of the mouth, whence it passes down the oesophagus, by means of 

 the action of the muscular fibres of that tube, into the stomach. The 

 mouth receives a copious supply of saliva from the parotid and sublingual 

 glands, and is thus kept sufficiently moist ; a state requisite to the exer- 

 cise of the sense of taste in full perfection, no less than to the muscular 

 use of the tongue : we here say nothing of the necessity of this fluid being 

 mixed with the food we swallow. It is in the mouth, then, that the first 

 preparation of our food for assimilation takes place, and nature has wisely 

 ordained, that, with this important duty, should be connected a sensation 

 of pleasure derived from the taste of agreeable viands. The sense of 

 taste is closely allied to that of smell ; both receive impressions from 

 the odorous particles of bodies : one from their volatile atoms mixed 

 with the air, the other from the bodies themselves only, when in con- 

 tact with the organ. The tongue, in Man, is covered with soft papillae, 

 invested with a thin cuticle, and appearing like the pile of velvet. In 

 the Cat tribe the papillae are horny, sharp, and retroverted : the tongue 

 of the Ox is villous towards its anterior part ; but the minute degrees 

 of difference, in the character of the surface of the tongue, need not be 

 here particularized. 



