Oculomotor Nerve in Scyllium canicula. 



567 



that, in his opinion, " the demonstration of the serial homology of head and 

 trunk metameres depends largely upon the proof of the resemblance of 

 eye-muscle and spinal somatic motor nerves." It seems to me that the 

 demonstration of the resemblance of the oculomotor (and other eye- 

 muscle nerves) to a complete spinal nerve (including sensory as well as 

 motor roots) would have even greater value in establishing the segmental 

 character of the head metameres. Thus, while I dissent from Neal's state- 

 ment just quoted, I am altogether in accord with his further statement 

 concerning the eye-muscle nerves that " failure to convince morphologists of 

 their meristic homology with spinal nerves would tend to undermine the 

 foundations of the traditional conception of the head." 



I desire to take this opportunity to acknowledge my indebtedness to 

 Prof. Dendy for valuable advice and criticism, and to Profs. Elliot Smith and 

 J. P. Hill for kindly directing my attention to the literature of the subject. 



LITERATURE. 



'10, Belogolowy, G., ' Zur Entwicklung der Kopfnerven der Vogel,' Moscow, 1910. 



'06, Carpenter, F. W., The Development of the Oculomotor Nerve, the Ciliary Ganglion, 



and the Abducent Nerve in the Chick." ' Bull. Mus. Comp. Zool.,' Harvard, 1906, 



No. 172. 



'89, Gaskell, W. H., " On the Delation between the Structure, Function, Distribution, 

 and Origin of the Cranial Nerves ; together with a Theory of the Origin of the 

 Nervous System of Vertebrates," ' Journ. Physiol.,' vol. 10 (1889). 



'09, Gast, R., ' Die Entwicklung des Oculomotorius und seiner Ganglien bei Selachier- 

 embryonen," ' Mitth. Zool. Stat. Neap.,' vol. 19 (1909). 



'99, Herrick, C. J., " The Cranial and First Spinal Nerves in Menidia," ' Journ. Comp. 

 Neur.,' vol. 9 (1899). 



'05, Johnston, J. B., " The Morphology of the Vertebrate Head from the Viewpoint of 

 the Functional Divisions of the Nervous System," 'Journ. Comp. Neur.,' vol. 15 

 (1905). 



'07, Johnston, J. B., ' The Nervous System of Vertebrates,' London, 1907. 



'11, Kuntz, A., " The Development of the Sympathetic Nervous System in Certain 



Fishes, ' Journ. Comp. Neur.,' vol. 21 (1911). 

 '03, Neal, H. V., "The Development of Ventral Nerves in Selachii," 'Mark Anniv. Vol., 



1903. 



'14, Neal, H. V., " The Morphology of the Eye Muscle Nerves," ' Journ. Morph.,' vol. 25 

 (1914). 



'80, Schafer, E. A., " Note on the Occurrence of Ganglion Cells in the Anterior Roots of 



the Cat's Spinal Nerves," ' Roy. Soc. Proc.,' vol. 31 (1880). 

 ; 05, Sedgwick, A., ' Student's Text-book of Zoology,' vol. 2, London, 1905. 

 '94, Sherrington, C. S., "On the Anatomical Constitution of the Nerves of Muscles," 



'Physiol. Soc. Proc.,' June 23, 1894, 1 Journ. Physiol.,' vol. 17. 

 '94a, Sherrington, C. S., "On the Anatomical Constitution of the Nerves of Skeletal 



Muscles ; with Remarks on Recurrent Nerves in the Ventral Spinal Nerve Eoot," 



'Journ. Physiol.,' vol. 17 (1894). 



