594 'Journal of Comparative Neurology and Psychology. 



motor and sensory fibers. The motor fibers are not so thick as 

 are those of the spinal nerves or those of the trigeminus. Even 

 the fibers of the VII nerve v^hich supply the m. hyo-hyoideus 

 anterior, a thick and active muscle, become much thicker than 



Fig. 20. 



Fig. 21. 



Fig. 20. Motor end plates from specialized muscles, a.a, two chains of end plates connected 

 with one motor fiber, m.f. b,c, somewhat more complex end plates; m, muscle fibers. Magnification, 

 300 diameters. 



Fig. 21. Motor endings in the sheath-muscle of a gill sac. The source of this figure is shown in 

 Fig. II. Magnification, 150 diameters. 



those which supply the branchial muscle. Still the motor fibers 

 are much thicker than the sensory fibers to the lining of the gill 

 sacs. The fibers ramify freely and the functional endings consist of 

 varicosities in the course of the terminal branches and simple knobs 



