MEDUSH, 31 
reflected, black in transmitted light. I noticed that a few of the cordyli of 
Ptychogena antarctica were chalk-white, and this conspicuous whiteness was also 
present in patches on the surface of some of the gonads. I am unable to explain the 
cause of the whiteness, but it is evidently due to minute particles, which are perhaps 
products of the decomposition of the endoderm. _ The white cordyli mounted in 
balsam show no cellular structure, but seem to be simply masses of granules. 
The two intermediate stages in the ‘Southern Cross’ collection taken on 19th 
May, 1899, are in a bad condition. Their connection with the large specimen, 
mentioned above, was traced by the shape of the basal bulbs of the tentacles and by 
the presence of the long club-shaped cordyli. The umbrella has the appearance of 
being hemispherical in shape, and measures about 25 mm. in width. The margin 
of the umbrella is crowded with tentacles, the number of which is estimated at about 
one hundred. Long cordyli were found between some of the tentacles, but not 
between every two tentacles. Their scarceness is no doubt due to the condition of the 
specimens. The better of the two specimens shows the gonads with the characteristic 
folds and a stomach. Unfortunately the stomach and gonads are compressed into a 
flat mass and matted together. Dissection could only be incompletely carried out 
awing to the rotten condition of the tissues. There is every appearance of a large 
central stomach, which hangs down in the umbrellar cavity, and a large mouth 
with a folded margin. The gonads extend along the radial canals from the base of 
the stomach nearly to the circular canal. The radial canals can be traced up to 
the centre of the umbrella, where they meet, and probably the stomach hangs down 
from them. 
Mr. Borchgrevink may have alluded to this species in his book “First on the 
Antarctic Continent,” p. 125: “10th May, 1899. In the forenoon I had discovered 
a small white clear jellyfish with a distinct blue cross in it.” The gonads of 
the two intermediate stages showed a deep bluish-black colour when, some years 
ago, I first examined them; but now the colour has changed to a dark brown 
(in alcohol). 
‘The single specimen in the ‘Discovery’ collection is in a fairly good state of 
preservation, but is mutilated and out of shape. It was useful for the description 
of the gonads, which are fairly perfect in this specimen and contain large ripe ova. 
The umbrella is rather thin, and is about 35 mm. in diameter. 
Ptychogena antarctica is distinguished from Ptychogena lactea by the absence of the 
conspicuous diverticula on the radial canals, and by the colour of the tentacles, which 
are red. 
Mr. Bigelow (1909) described a new species—P. erythrogonon, from the eastern 
tropical Pacific (between Galapagos Islands and Callao). It has well-marked specific 
characters, possessing a very thick globular umbrella and about 80 tentacles. Its 
coloration is a very brilliant brick-red. 
