574 
PROFESSOR E. A. SCHAFER ON THE 
Fig. 19. A small portion of entoderm lining the nutritive canal near the fovea nervosa 
inferior, with two delicate processes of (mesodermic ?) cells, simulating 
nerve-fibres, passing towards the epithelium of the canal. 
Fig. 20. Vertical meridional section through the margin of an Aurelia near one of the 
lithocysts, showing the rudimentary organ described in the text (note 
to p. 569). The extremely dark appearance imparted to it is a mistake of 
the engraver. 
ect. Bell-shaped projection formed of thickened ectoderm and occupied 
by a prolongation of the nutritive canal, n.c. ; the thickened 
entoderm of which is seen to pierce its ectodermic covering and 
project as an otolithic clump, o.c. 
ect'. Ectoderm of under surface. 
ect" Ectoderm of upper surface of umbrella. 
m. Mesoderm. 
r.n.c. Radial nutritive canal cut obliquely. This is seen to be connected 
to other canals by a layer of entodermic cells, end., indicating an 
adhesion of originally separated tracts, such as are seen in Chrysaora. 
Postscript. 
(Received October 16, 1878.) 
It was not originally my intention, in submitting my observations upon the nervous 
system of Aurelia aurita to the Enyal Society, to add to the length of the com- 
munication by introducing an account of the general literature of the Medusae, and 
for this reason : that in looking through the various papers upon the subject to which 
I had access I could find no observations (beyond those of Haeckel, referred to at the 
beginning) that had any direct bearing upon the immediate subject of this article. 
I was fully aware of the fact that fibres had been described in the jelly-like tissue, and, 
more than this, I was familiar •with the aspect of these fibres ; but since both from 
their situation and appearance there could be no idea of their nervous nature, or of 
their having any connexion with those described in this paper, it seemed to me 
unnecessary to refer specially to them. And the same with regard to previous obser- 
vations upon the “ marginal bodies,” which had not before, so far as I knew, been 
submitted to the more modern methods of histology, and especially had not been 
examined by means of sections, which are necessary for throwing light upon the 
intimate structure of such objects. But my friends thought differently, and, yielding 
to their advice, I was preparing an account of the literature of the Medusae to take 
the form of an Appendix to this article, when the appearance, in the spring of this year, 
