MR. G. J. ROMANES ON THE LOCOMOTOR SYSTEM OF MEDUSAE. 199 
Ostsee/ Berlin, 1836; Kolliker, ‘Ueber die Randkorper der Quallen, Polypen und 
Strahlthiere/ Froriep’s neue Notizen, bd. xxv., 1843 ; Yon Beneden, “ Memoire sur les 
Campanulaires de la cote d’Ostende,” £ Memoires de l’Academie cle Bruxelles/ vol. xvii., 
1843 ; Desor, “Sur la generation medusipare des Polypes hydraires,” ‘Annales d. 
Scienc. Natur. Zool.,’ ser. iii., t. xii., p. 204; Krohn, “Ueber Podocoryna carnea,” 
‘Archiv. f. Naturgescbicbte/ 1851, b. i. ; McCrady, “Description of Oceania, &c.,” 
‘Proceedings of the. Elliot Society of Natural History/ vol. i., 1859; L. Agassiz, 
“Contributions to the Acaliphae of North America,” ‘Memoirs of the American 
Academy of Arts and Sciences/vol. iii., 1860, vol. iv., 1862; Leuckart, ‘ Archiv. f. 
Naturgeschichte,’ Jahrg. 38, b. ii., 1872 ; Hensen, “ Studien liber das Gehororgan der 
Decapoden,” ‘Zeitsclir. f. wiss. Zool./ bd. xiii., 1863; Semper, “ Peisebericht,” ‘ Zeitschr. 
f. wiss. Zool./ bd. xiii., u. xiv. ; Claus, “Bemerkungen liber Cienophoren und Medusen,” 
‘Zeitschr. f. wiss. Zool.,’ bd. xiv., 1864; Allman, “ Note on the Structure of Certain 
Hydroid Medusae,” Brit. Assoc. Rep., 1867 ; Fritz Muller, “Polypen und Quallen von 
S. Catharina,” ‘Archiv. f. Naturgesch./ Jahrg. 25, bd. i., 1859 ; also “ Ueber die Rand- 
blaschen der Hydroidquallen,” ‘Archiv. f. Anatomie und Physiologie/ 1852. 
A brief sketch of the contents of these and other memoirs on the histology of the 
Medusae is given in Drs. Hart wig recently published work on the nervous system 
and sense organs of the Medusae, and these authors point to the important fact 
that before the appearance of Haeckel’s memoir, Leuckart was the only observer who 
spoke for the fibrillar character of the so-called marginal ring-nerve; so that in 
ILeokel’s researches on Gergonia, whereby both true ganglion cells and true nerve- 
fibres were first demonstrated as occurring in the Medusae, we have a most important 
step in the histology of these animals. Haeckel’s results in these respects have since 
been confirmed by Claus, ‘Grundziige der Zoologie/ 1872 ; Allman, ‘A Monograph 
of the Gymnoblastic or Tubularian Hydroids/ 1871 ; Harting, “Notices Zoologiques,” 
Niederlandisches ‘Archiv. f. Zool./ bd. ii., Heft 3, 1873 ; F. E. Schulze, ‘Ueber den 
Bau von Syncorzne Sarsti / O. and R. Hertwig, ‘Das Nervensystem und die Sinnes- 
organe der Medusen ; ’ and possibly also by Eimer in his forthcoming publication. 
Of these memoirs by far the most important is that of Drs. Hertwig. These 
authors state that their investigations were completed before the physiological investi¬ 
gations of Dr. Eimer and myself had fallen under their notice ; so that, as they remark, 
the agreement of their morphological with our physiological results is rendered by this 
independence the more valuable. In the present paper it will be impossible for me to 
render a full account of the important work which all scientific naturalists will consult 
for themselves. I will therefore confine myself to epitomising the lucid epitome which 
Drs. Hertwig give of their own histological results. 
There is so great and fundamental a difference between the nervous system of the 
naked- and of the covered-eyed Medusae, that a simultaneous description of the nervous 
system in both groups is not by these authors considered practicable. Beginning, 
therefore, with the naked-eyed division, they describe the nervous system as here con- 
