MEDUSA. 21 
Another species placed by Professor Haeckel in the genus Rathkea is Cytzs 
octopunctata of Sars (1835). This species is fairly well known and has been found in 
the Arctic regions and in the North Atlantic, along the coast of North America, and 
also along the coast of Europe, from Norway to about as far south as the English 
Channel. There is no evidence that the species occurs in the Mediterranean. Cytexis 
octopunctata belongs to the genus Margellium Haeckel. It has four radial canals, 
eight groups of tentacles, and a peculiar mouth. The mouth has the appearance of 
possessing four perradial tentacles, each of which is distally bifurcated and terminates 
with a small globular cluster of nematocysts. These are not true tentacles, but simply 
the four corners of the mouth stretched out so as to resemble stalks. The clusters ot 
nematocysts are really on the margin of the mouth and there is no mistaking their 
position when the mouth is seen wide open. 
fathkea fasciculata (Péron, 1809) is the third and last species mentioned by 
Prof. Haeckel. This species is well known and has been described and figured by 
Gegenbaur (1856), by Keferstein and Ehlers (1862) under the name of Lizzia hoellikeri, 
and by Leuckart (1856) under the name of Bougainvillia koellikeri. It was originally 
named by Péron Melicerta fasciculata, and was transferred by L. Agassiz (1862) to a 
new genus called Koellikeria, because Melicerta was a pre-occupied name. This Medusa 
has four radial canals, eight groups of tentacles on the margin of the umbrella, and 
four perradial oral tentacles which are very much branched. The oral tentacles arise 
a little way from the margin of the mouth, which has four Hips without any clusters of 
nematocysts upon them. The species is confined to the Mediterranean, and is well 
known at Naples by the name of Lizzia koellikeri. , 
I do not think that &. blumenbachi belongs to the same genus as £. fascicularis, 
as Rathke’s drawing of the mouth does not represent branched oral tentacles, such as 
R. fascicularis possesses. It is also necessary to bear in mind that Rathke figured 
eight radial canals. 
For the classification of the Margelide it is necessary to know not only the 
number of groups of marginal tentacles, but also whether the species has definite oral 
tentacles (which may be branched or unbranched) or only clusters of nematocysts on 
the margin of the mouth. Under the circumstances I think it is best to give Rathkea 
fascicularis another generic name, and to place vathkea blumenbacht on the dormant 
list until we really know something more about it. There is not much to be gained by 
retaining a badly described type species, as it only leads to confusion. 
I think it will be an advantage to use in future the name Koellikeria for the genus, 
and then fascicularis will become the type species. To this genus should be transferred 
Rathkea octonemalis, Maas (1905), found at Ternate, and Lizzia elegans, Mayer (1900), 
found off Tortugas, Florida. I am also rather inclined to include Chiarella centripetalis, 
Maas (1897). Chiarella is distinguished from the other genera of the Margelide by 
possessing a double bundle of tentacles in each of the eight groups, and by having 
interradial extensions of the circulay canal, but these are almost too slight to be called 
Y 2 
