MAMMALIA. 



135 



branch to the internal pterygoid muscle ; others are given to this muscle by the otic 

 ganglion. The gustatory nerve exists only in mammalia; it receives the cord of 

 the tympanum, it passes between the external and internal pterygoid muscles, next 

 underneath the membrane lining the mouth, and then between the lingual muscle and 

 the insertion of the genio-hyoideal, and divides into branches ; some of which com- 

 municate with others of the ninth, and pass upwards to terminate in the papillae at 

 the anterior and middle portions of the surface of the tongue ; it gives branches also 

 to the salivary glands, and a considerable one to be distributed on the portion of the 

 membrane of the mouth connecting the side of the tongue with the lower jaw. In 

 some animals, as in man, it is difficult to determine whether the branches do not give 

 filaments to the muscles in passing to the surface of the tongue. The gustatory nerve 

 is rather larger in proportion to the size of the tongue in man than in the baboon, and 

 in this than in the sheep, goat, calf, and ass ; and in these than in the dog, and in this 

 than in the jaguar. The coarseness of the texture of the fibrils is, however, generally 

 in the reverse order, except in man and the baboon, it being the greatest in the sheep, 

 goat, calf, and ass, and least in the dog and jaguar. The cord of the tympanum is 

 almost peculiar to mammalia ; a resemblance of it has been traced in birds. In the 

 calf, it begins at the hard portion, and passes across the membrane of the tympanum, 

 nearly as in man ; it communicates with the tympanine nerve of the glosso-pharyngeal, 

 and the sympathetic on the outside of the petrous portion forming one surface of the 

 tympanum ; it passes downwards, and at length becomes intimately united with about 

 an inch of the gustatory nerve ; a nerve is again given off from the side at which the 

 cord of the tympanum joined the gustatory ; this communicates with two other 

 branches, and is then distributed on the posterior part of the surface of the tongue ; 

 by dividing communicating filaments this might be made into a continuation of the 

 cord of the tympanum ; but it would be a deception. In the ass, it is in apposition 

 with the gustatory nerve for a short distance, and then becomes intermixed with fibrils 

 of this nerve. In the dog, it becomes intimately conjoined with the gustatory. In 

 the goat, it forms a distinct oval ganglion close to the tympanum, which sends 

 filaments into this, and then descends and joins the gustatory nerve, with the fibres 



