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PROFESSOR E. RAY LANKESTER. 
whole margin of the umbrella, and in close relation with the 
otolitic cells. Ocelli are not present. 
The generative sacs are borne on the radiating canals, into 
which they open at a short distance beyond the exit of these from 
the base of the manubrium. They are of an oval form, and from 
their point of attachment to the radial canal hang down free into 
the cavity of the umbrella. Some of the specimens examined 
contained nearly mature ova, which, under compression, were 
forced from the sac through the radial canal into the cavity of 
the stomach. 
While some of the characters described above point to an 
affinity with both the Trachomedusse and Narcomedusse, this 
affinity ceases to show itself in the very important morphological 
element afforded by the marginal bodies. In both Trachomedusse 
and Narcomedusse the marginal bodies belong to the tentacular 
system ; they are metamorphosed tentacles, and their otolite 
cells are endodermal, while in the Leptomedusse, the only other 
order of craspedotal Medusae in which marginal vesicles occur, 
these bodies are genetically derived from the velum. Now, in 
Limnocodium the marginal vesicles seem to be as truly velar as 
in the Leptomedusae. They occur on the lower or abumbral side 
of the velum, close to its insertion into the umbrella, and the 
tubular extension of their capsule runs along this side to the free 
margin of the velum, while the delicate epithelium of the 
abumbral side passes over them as in the Leptomedusae. It is 
true that this point cannot be regarded as settled until an oppor- 
tunity of tracing the development is afforded ; but in very young 
specimens which I examined I found nothing opposed to the view 
that the marginal vesicles were derived, like those of the Lepto- 
medusae, from the velum. 
If this be the case Limnocodium will hold a position inter- 
mediate between the Leptomedusae and the Trachomedusae ; but 
as the greatest systematic importance must be attached to the 
structure and origin of the marginal vesicles, its affinity with the 
Leptomedusae must be regarded as the closer of the two.” 
It will be observed that, in opposition to the results which I 
had published in the previous week. Professor Allman holds 
that the structures which I had identified with the peronia 
(tentacle-rivets or Mantelspangen) of Trachyline Medusae are 
not true peronia ; ” further, that the tentacles, though solid, do 
not present the chorda-like endodermal axis ” characteristic of 
Trachomedusae and Narcomedusae, and lastly, that the otolite 
cells are not endodermal, as in Trachyline Medusae, but are de- 
rived from the ectoderm of the velum, as in Leptomedusae, and 
on this ground especially he holds that the affinity of the new 
