1916. | R. E. Luovp: Campanulina ceylonensis. 57 
The Free Medusa. 
The medusa was described by Browne from specimens taken 
in the sea off Ceylon, and its systematic position has heen dis- 
cussed by Dr. Annandale in the first part of this paper. It is 
therefore unnecessary to say much more beyond reference to the 
peculiar condition under which the organism was found in Calcutta. 
The unusual and sudden appearance of a swarm of medusae in a 
‘brackish canal—far removed from the sea though connected at one 
point with the tidal waters of the Hooghly—make it most likely 
that the medusae were all of one species. An examination showed 
beyond doubt that the many hundreds of specimens taken by the 
tow-net were indeed of one species though varying very much in 
appearance according to age and state of activity. Plate vii, 
fig. I gives some idea of the appearance presented by a number 
of the medusae at the time of capture. At first sight one might 
suppose that they included several distinct species. The largest, 
bearing ripe gonads, measured about 2°5 cm. in diameter, the 
height of the bell during relaxation being about two-thirds of the 
diameter, but specimens preserved in formalin are usually flatter 
than this. Half-grown specimens, especially when swimming 
actively, appear higher than they are broad and in this condition 
the tentacles may stream out to a length two or three times 
greater than the height of the bell. When resting they assume a 
flatter shape and the tentacles are considerably contracted. In 
this condition the peduncle and manubrium together can often be 
seen revolving about the fixed base. While so engaged the mouth 
and lips appear to clean the tentacles and search the groove 
between the velum and inner wall of the bell for adherent food 
particles. 
The smallest specimens, measuring 2-3 mm., show certain differ- 
ences from the mature form. The peduncles of the manubrium, 
which is a characteristic feature of the adult, is scarcely repre- 
sented, The sense vesicles are less numerous than the tentacles, 
nor are they so regularly disposed in alternation with the tentacles 
as in the adult; but this is only to be expected at a time when 
the tentacles are rapidly increasing in number. Plate vii, fig. 4 
shows a young medusa with eight tentacles, six sense vesicles and 
a number of tentacular buds. At this time the primitive germ 
cells are distinctly visible and they can be seen even before the 
medusa has left the gonosome. 
In the mature condition the generative cells are disposed along 
the radial canals from the base of the peduncle to the margin of 
the bell. They form prominent ridges with a somewhat contorted 
edge which projects from the lower surface of the bell. A sec- 
tion across one of these ridges shows the radial canal lined by 
attenuated columnar cells between which and the very delicate 
ectoderm the generative cells lie. 
PO NI NAA DIN PNT A 
