EXPLANATION OF PLATE XVI. 



Complete list of references. 



V. fifth nerve. 



V. op. th. ramus ophthalmicus of fifth nerve, 

 \.mx. „ maxillcTG superioris of fifth nerve. 



Y. m7i. „ mandibularis of fifth nerve, 



vii. seventh nerve. 



vii. i7in. mandibular (spiracular) branch of seventh nerve. 

 vii. hi/, hyoid branch of seventh nerve, 

 vii. a. anterior branch of seventh nerve. 

 gl. glossopharyngeal nerve. vff. vagus nerve. 



vg. r. roots of vagus nerves in the brain. 



vg. com. commissure uniting the roots of the vagus, and continuous 

 with commissure uniting the posterior roots of the spinal nerves. 

 vg. in. intestinal branch of vagus. 

 Tg. br. branchial branch of vagus. 



n I. nervus lateralis. p r. posterior root of spinal nerva 



a r. anterior root of spinal nerve. v c. visceral cleft. 



sp. spiracle. au. v. auditory vesicle. op. eye. 



ol. olfactoiy pit. cer. cerebrum. ch. notochord. 



p ch. parachordal cartilage. II. lateral line. 



pjy, head cavity. hy. m. hyaloid membrane. 



pfal. processus falciformis. rt. retina. 



ch. epithelial layer of choroid membrane. v h. vitreous humour. 



Fig. 1. Diagram of cranial nerves at stage L. 



A description of the part of this referring to the vagus and glosso- 

 pharjTigeal nerves is given at p. 2U3. It should be noticed that there are 

 only five strands indicated as springing from the spinal cord to form the 

 vagus and glossopharyngeal nerves. It is however probable that there are 

 even from the first a greater number of strands than this. 



Fig. 2. Section through the hinder part of the medulla oblono^ta, 

 stage between K and L. Zeiss A, ocul. 2. * 



It shews (1) The vagus commissure with branches on one side from the 

 medulla. (2) The intestinal branch of the vagus giving off a nerve to the 

 lateral line. 



Fig. 3. Longitudinal and vertical section through the head of a 

 Scy Ilium embryo of stage L. Zeiss a, ocul. 2. 



It shews the course of the anterior branch of the seventh nerve (vii) ; 

 especially with relation to the ophthalmic branch of the fifth nerve (v. o. th.). ' 



Fig. 4 a and 4 h. Two horizontal and longitudinal sections through the 

 head of a Scyllium embryo belonging to stage 0. Zeiss a, ocul. 2. 



4 a is the most dorsal of the two sections, and shews the course of the 

 anterior branch of the seventh nerve above the eye. 



4 ft is a slightly more ventral section, and shews the course of the fifth 

 nerve. 



