Ixxii Journal of Comparative Neurology. 



the Rodentia."! The Hyrax according to this classification would be- 

 long to the group which he calls Canorhinaia. 



H. HEATH BAWDEN. 



Ruge on the Facial Nerve. ^ 



The motor portion of the seventh cranial nerve was studied in con- 

 nection with the corresponding musculature in representatives of nearly 

 all classes of craniote vertebrates in order to determine the homologies 

 from the lowest Selachii to man. In view of the fact that in the lower 

 vertebrates the seventh nerve is mainly sensory with a small motor 

 component for the deep seated visceral muscles of the hyoid arch, 

 while in the higher mammals it is almost wholly motor, and that too 

 for the superficial muscles of expression of the face, — in view of this 

 remarkable transformation, the task to which the author has addressed 

 himself is one of extreme difficulty. The problem, however, is greatly 

 simplified when we remember, on the one hand, that of the sensory 

 faciahs fibers of the fishes the greater part belong to the lateral line 

 system and with the disappearance of this system all of these cutane- 

 ous fibers are in consequence totally wanting in higher vertebrates ; 

 and, on the other hand, that in the ontogeny of man the facial muscles 

 of expression arise (as cited by Ruge from Rabl) in the neighborhood 

 of the hyoid and hence are to be regarded as derivations of the hyoid 

 musculature. 



In the introductory general section the seventh nerve is shown to 

 be in fishes a typical branchiomeric nerve, like the ninth and tenth, 

 supplying the spiracular cleft, and comprising a pharyngeal branch (r. 

 palatinus), a pre-trematic branch (in some sharks) and a post-trematic 

 branch (truncus hyo-mandibularis). 



In the comparative anatomical section the selachians are treated 

 with especial fulness and the attempt is made to derive all other forms 

 from this. In the sharks we have (following Vetter) a system of super- 

 ficial constrictor muscles in the region supplied by the facialis in which 

 five members are designated ; (i) a superficial dorsal maxillary por- 

 tion ; (2) a ventral mandibular portion ; (3) a deeper dorsal hyoid por- 

 tion ; (4) a ventral hyoid portion ; (5) a superficial dorso-ventral por- 



• A Contribution to the Comparative Anatomy of the Mammalian Organ of 

 Jacobson. Trans. Roy. Soc. Ed., Vol. XXXIX, pt. i, 1S97, p. 251-252 (a valu- 

 able bibliography is here appended). 



" Ueber das peripherische Gebiet des Nervus facialis bei VVirbelthieren. 

 By Dr. Georg Ruge. With 76 text-figures. Festschrift f. Gegenbaur, III, 

 Leipzig, 1897, pp. 193-348- 



