6 EDWARD T. BROWNE. 
side, a lateral outgrowth of the umbrella. This outgrowth 
contains two colleto-cystophors and two groups of tentacles, 
one behind the other. The specimen has altogether ten groups 
of tentacles and ten colleto-cystophors. 
The Regeneration of Injured or Lost Organs.— 
It is evident from the mutilated condition of some specimens 
that a considerable amount of injury may happen to the 
umbrella without causing death to the medusa. The damaged 
or lost organs may be replaced by new ones, which may or 
may not resemble the old ones. A new symmetry may even 
arise through a decrease in the number of organs, which in 
some cases might be mistaken for congenital variation. The 
simplest case is the loss of one group of tentacles, well illus- 
trated by aspecimen (fig. 21) which has all its organs perfectly 
normal except that one group of tentacles is missing. The 
prolongation of the umbrella and the genital band suddenly 
terminates, as if the tentacles had been cut off with a knife. 
Another specimen (fig. 22) shows a similar abrupt termination 
of the genital band, but a few short tentacles are present which 
may be reasonably regarded as anew growth. The destruction 
and regrowth of tentacles are also well shown in a specimen 
(fig. 16) with five normal groups and with two groups having 
only a few short tentacles. A genital band and a short pyro- 
longation of the umbrella marks the position of the eighth 
group which is missing. 
Two specimens show both congenital variation and an 
abnormality due to regeneration. One of these (fig. 14) has 
three septa, five genital bands (the sixth is absent, but its posi- 
tion is faintly marked), and six colleto-cystophors ; but there 
are only four normal groups of tentacles present. The other 
two groups have evidently been destroyed and are again budding 
out afresh. The other specimen (fig. 17) has three septa, 
seven genital bands, six colleto-cystophors, and only four normal 
groups of tentacles. One half of the umbrella, containing these 
groups of tentacles, is normal in shape, but the other half has 
apparently been destroyed, and three new groups of tentacles 
are in the process of development. 
