ELISHA MITCHELL SCIENTIFIC SOCIETY 90 
point well worth working up, more especially as it is not 
confined to the Cubomeduse, but has been observed in 
the ephyra lobes of discophores (/?hizostoma). 
Before leaving this subject of the general body-plan, it 
may be mentioned that while the probability is that the 
Cubomeduse are descended from stalked ancestors (Lz- 
cernaria-like forms), and hence that the apex of the ex- 
umbrella was ence drawn out into a peduncle, there is in 
the adult Cubomedusa no trace externally or internally 
of this hypothetical stalked condition. Light on this 
very interesting point can only be expected from a study 
of the development. 
Unlike the other Scyphomedusze studied, the Cubome- 
dusz possess a nerve ring. In their study of the nervous 
system Claus and Conant both depended on sections, and 
naturally the results are not so satisfactory as those 
reached by the Hertwigs on the Hydromeduse mainly 
with the aid of macerations. Claus describes the neuro- 
epithelium as consisting of alternating supporting cells 
and sensory cells, the inner ends of the latter becoming 
continuous with the nerve fibres. Conant makes it 
doubtful whether this is the actual condition, since he 
does not find the sensory cells. He offers, however, no 
observations on the origin of the ‘nerve fibres.’ Macera- 
tions will probably show the connection of these fibres 
with at least some of the neuro-epithelium cells. 
The possession of a nerve ring has been regarded (Claus) 
as a point of essential similarity between the Cubomedu- 
sae and the Craspedota. The main ring in the former 
group is obviously a differentiation of the suabumbrellar 
epithelium, and Claus, therefore, interprets it as homolo- 
gous with the inner Craspedote ring. In the immediate 
neighborhood of each sense organ there are given off from 
the main ring two roots which ceasing to be superficial 
bands pass through the jelly, and emerge on the outer wall 
