NERVOUS SYSTEM AND SENSE ORGANS OF AMIURUS. 453 



PLATE VI. 



BO. — Basi-occipital. 



G. I. — Centrum of 1st vertebra. 



D M. — Dorsal musculature. 



E O. — Exoccipital. 



L. tri. — Trigeminal lobes. 



L. vag. — Vagus lobes. 



jV. VIII. post. — Posterior division of auditory nerve. 



R. ac. vag. I — Acustic root of vagus. 



R. lag.— Ramus lagena? cochlear 



R. lat. V. — Pvamus lateralis trigemini. 



R. sac. — Ramus sacculi. 



T. A . — Tuberculum acusticum. 



Vag. — Vagus nerve. 



as. — Asteriscus. 



asi. — Atrium sinus imparis. 



cr. — Crest of basi-occipital between fovea? sacculi. 



cl. — Claustrum. 



d 1 2 3 — Dorsal roots of 1st, 2nd and 3rd spinal nerves. 



de. — Ductus endolymphaticus. 



dm. — Patch of dura mater on basi-occipital and upper surface of 

 first vertebra. 



dus. — Wall of ductus utriculo-saccularis. 



fr. — Frontal semi-circular canal. 



fr. a. — Ampulla of semi-circular canal. 



fs. — Fovea sacculi. 



in. — Incus. 



lag. — Lagena cochleae. 



na I. — Neural arch of 1st vertebra. 



mall. — Malleus. 



s. — Sagitta. 



sac — Sacculus. 



sc. — Saccus endolymphaticus. 



sp. — Saccus paravertebralis. 



St. ant. — Anterior spoon-shaped process of stapes. 



st. art. — Articular process of stapes. 



st. asc. — Ascending process of stapes. 



St. t. — Tendon attaching incus to stapes. 



u. — Utriculus. 



v i 2 s — Ventral roots 1st, 2nd and 3rd spinal nerves. 

 Figs. 1-11 represent selected sections from a frontal series through the part 

 surrounding the central nervous system of Amiurus from the posterior face of 

 the first vertebra as far forward as the suture between the ex-occipital and 

 the prootics. 

 Yia, 1. The dorsal and ventral roots of the third spinal nerve piercing the 



membranous wall of the neural canal, which is lined by the dura 

 mater vertebralis, while the spinal cord is closely invested by 



