150 



VISION 



A sm 



10 



smio ir 



m y| 



mlf 



2 mm 



Figure 21 Transverse sections through the caudal hindbrain of the clearnose skate, Raja 

 eglanteria. The levels of these sections and those illustrated in Figures 20, 22, and 23 are 

 indicated in Figure 16B. cc, cerebellar crest; de, descending tract and nucleus of VIII; dn, 

 dorsal nucleus of the anterior lateral line lobe; dt, descending trigeminal tract; dv, de- 

 scending trigeminal nucleus; io, inferior olive; ir, inferior raphe nucleus; irf, inferior 

 reticular formation; lrz, lateral reticular zone; mlf, medial longitudinal fasciculus; ni, 

 nucles intermedius of the posterior lateral-line lobe; nl, nucleus of the lateral funiculus; 

 nx, vagal motor nucleus; plln, posterior lateral-line nerve; rx, roots of the vagal nerve; sm, 

 spinal motor column (hypoglossal nucleus); vl, vagal lobe (nucleus solitarius); w, nucleus 

 w (possible lateral vagal motor nucleus or primary sensory neurons). 



and descend throughout the brain stem and arise from a number of different 

 sources. All existing vertebrate experimental data indicate that the vestibular 

 nuclei form extensive connections with the extrinsic eye muscle nuclei via 

 the medial longitudinal fasciculus. Experimental evidence for Dasyatis 

 indicates that the axons of nucleus interstitialis extend from midbrain 

 levels into the spinal cord (R. B. Leonard, personal communication). 



