SUMMARY. 237 



when it supplies supernumerary muscles ; in man, it arises from the oblique tract of the 

 annular tubercle, and in mammalia, from the trapezoid body ; in the other classes it 

 arises from the oblong medulla. It communicates with the sympathetic in man and 

 the monkey in a similar manner, but in other animals, rather differently. The auditory 

 is present in the four superior classes ; it arises in all from the oblong medulla, and 

 in mammalia a portion of it is traced to the surface of the fourth ventricle ; in some 

 fishes it is a branch of the fifth, it may therefore be presumed that much difference 

 between it and the fifth does not generally exist. Its distribution varies in some 

 degree according to the shape of the labyrinth. The hard portion exists in the three 

 superior classes ; it arises from the oblique tract of the annular tubercle in man, and 

 from the trapezoid body in mammalia. In birds and amphibia its size is less than in 

 mammalia, as the muscles of the face are absent. The glosso-pharyngeal nerve exists 

 in the four superior classes ; its origin is from the involuntary centre in man, mam- 

 malia, and birds, and from analogous parts in amphibia and fishes. In mammalia, 

 besides the other distributions, it sends filaments into the tympanum ; it supplies the 

 back of the tongue and the anterior part of the epiglottis ; in birds it is larger in 

 proportion to the par vagum than in any of the other classes, and communicates 

 more with the sympathetic ; it gives the branch to the glottis, which in mammalia 

 is furnished by the par vagum, and supplies the tongue as far as the tip ; in amphibia 

 it is in some respects the same as in birds ; in the snake it supplies the glottis, whilst 

 the par vagum does that of the turtle as in mammalia; in fishes, its origin is 

 connected with that of the par vagum, and it supplies the first gill and part of the 

 membrane of the throat ; in three classes it is connected with the organ of hearing, 

 but not in the turtle, the par vagum rather supplies its place. The pharyngeal plexus 

 is the most complicated in man, next in mammalia; in some birds and amphibia, 

 as the pelican, crane, and snake, the combination of nerves is much greater than in 

 the goose and turtle ; but in fishes the pharynx is supplied by branches of the par 

 vagum along with the stomach. The par vagum exists in the four superior classes, 

 and is not very different ; its origin is from the involuntary centre in man, mammalia, 

 and birds, and from analogous parts in amphibia and fishes; it, as well as some 



