595 



The Facialis proper arises by two roots (Fig. 7), a large dorsal 

 root from the anterior end of the Lobus vagi, distributed entirely to 

 the mucosa of the mouth and the region of the hyoid arch, and a 

 ventral root which supplies muscles of the opercular region. (Stannius, 

 fourth and fifth roots, Goronowitsch, Ewart, Cole '96, Pinkus.) 



The N. lineae lateralis arises by three roots (Figs. 6 and 7). Two 

 arise anterior and dorsal to the Acusticus and Facialis proper, one 

 from the Lobus lineae lateralis (L. trigemini of Goronowitsch) and 

 one from the tuberculum acusticum. (Stannius, second and third 

 roots, Goronowitsch, T. II d., and T. II v., colored r e d in Fig, 82.) 

 The third root arises from the tuberculum acusticum dorsal and 

 posterior to the Acusticus. The first two roots are referred to in this 

 paper as the lateral line Vllth., and the third as the lateral line Xth. 

 They supply the canal organs and related structures of the head and 

 body. (Stannius, Goronowitsch, Ewart, Pinkus, Cole, Allis '97, 

 Strong.) 



The Acusticus arises from the ventral part of the tuberculum 

 acusticum dorsal to the spinal Vth. tract, and supplies the ear. 



The Glossopharyngeus arises by a dorsal root from the Lobus 

 vagi and a ventral root from the Fasciculus longitudinalis posterior 

 (Fig. 5), the Vagus arises by several similar dorsal and ventral roots 

 (Fig. 4), and both are distributed wholly to muscles and mucosa of 

 the branchial region and to other visceral structures. The presence 

 in these nerves of spinal Vth. fibres with cutaneous distribution should 

 be borne in mind. (Stannius, Goronowitsch, Strong.) 



The Oculomotor, Trochlearis, Abducens, and Hypoglossus are 

 wholly motor and are not of interest in the present connection. 



The sensory structures of the integument of the head in fishes 

 include free nerve endings, usually referred to as "general cutaneous 

 structures", terminal buds, pit organs, canal organs, ear, vesicles of 

 Savi, and ampullae of Lorenzini. The last two structures have not, 

 to my knowledge, been described in Acipenser, The terminal buds, 

 pit organs, canal organs, and ear have been shown by Ayers ('92) 

 and others to be homologous organs. These several structures are 

 innervated as follows: the general cutaneous structures and terminal 

 buds (?) by the Vth., the pit organs and canal organs by the lateral 

 line nerves, and the ear by the Vlllth, The general cutaneous 

 structures are supplied chiefly or wholly by spinal Vth. fibres, a con- 

 siderable number of which enter the medulla by way of the Vagus 

 and other roots. The ampullae of Lorenzini, in those fishes in which 

 they occur, are innervated by the lateral line Vllth. (Ewart '89, 



41* 



