102 SIDNEY F. HARMER. 
owe its origin to the oldest zocecium which is formed asa bud 
and does not result from the metamorphosis of the larva; or, 
in other words, the ovicell tends to be formed from the first 
blastozoite of the colony. I have found no case in which the 
ovicell owes its origin to z'; but it must not therefore be con- 
cluded that the primary individual differs from the others in 
being devoid of generative organs. z! commonly has a well- 
developed testis, while I have on several occasions observed 
structures in z! which I consider to be egg-cells. 
It will be seen from the figures of the entire colonies that the 
determination of z®? and z? is easy enough in sections in many 
cases in which the orientation is good. It is more difficult 
when, as commonly happens, the disc from which the colony 
originates is injured or lost when the Lichenopora is removed 
from the seaweed. The determination of the fertile zocecium 
is greatly facilitated by noticing the position of the tentacles of 
the polypides. 
The woodcut on p. 78 shows that z! may be considered to 
have an inner (axial) and an outer side. During the retracted 
condition of the polypide the tentacles lie close to the inner 
side of the zocecium, while the cecum of the stomach is situated 
more externally. The orientation of the polypide of z’ is like 
that of the polypide of z'; but the polypide of z* faces in the 
opposite direction, its tentacles lying, like those of z!, close to 
the inner border of the zoccium. ‘This appears to be true of 
all the polypides developed in any zocecium. After a given 
polypide has degenerated into the condition of a brown body, 
the newly formed polypide is found to have the same orienta- 
tion of its tentacles as its predecessor had. The younger 
zocecia have a corresponding arrangement. In any colony the 
polypides are normally orientated during retraction in such a 
way that the tentacles of a polypide are nearer to the centre of 
the circle enclosed by the growing margin of the colony than 
is the stomach. This point is, however, not brought out by 
any of the figures which illustrate this paper. It may be noted 
that the number of the tentacles is constantly eight. 
A further point which deserves special notice is the character 
