OBSERVATIONS ON THE CRANIAL NERVES OF SCYLLIUM. 



By A. Milnes Marshall, M.A., D.Sc, Professor of Zoology in Owens 

 College; and W. Baldwin Spencer, of Oivens College. 



[Plates V— VI.] 



The investigations recorded here were undertaken in the first instance 

 for the purpose of controlling certain determinations published by one 

 of us in a previous number of this journal 1 concerning the cranial 

 nerves of Elasmobranchs. To this end we have carefully re-examined 

 the specimens upon the investigation of which the former account 

 was based, and have, in addition, made a large number of new 

 preparations, illustrating more especially the later stages of develop- 

 ment — stages m to q of Balfour's nomenclature. 2 



During the course of our work so many altogether new and unex- 

 pected points were brought to light, that we soon found it necessary 

 to widen considerably the scope and limits of our investigations, and 

 have finally been led to attempt a complete account of the development 

 of the cranial nerves from stage k to the adult form, and to endeavour 

 in this way to connect together directly the accounts previously given 

 of the early stages 3 with the descriptions of the nerves of adult Elas- 

 mobranchs published by Stannius, 4 Gegenbaur, 5 and other anatomists. 6 



1 Marshall, " On the Head Cavities and Associated Nerves of Elasmobranchs," 'Quart. 

 Journ. Micr. Sc, Jan., 1881, pp. 71 seq. Future references will be to this paper unless 

 otherwise specified. 



B Elasmobranch fishes, pp. 79 and 80. 



3 Balfour, op. cit. Marshall, loc. cit. 



4 Stannius, ' Das peripherische Nervensystein der Fische,' Rostock, 1819. 



5 Gegenbaur, "Die Kopfnerven von Hexanchus," ' Jen'aische Zeitschrift,' Bd. vi. 



6 JSsp. Jackson and Clarke, "The Cranial Nerves of Echinorliinus spi?iosus," 'Journal 

 Anatomy,' vol, x. 



