98 SIDNEY F. HARMER. 
A much larger number of degenerating embryos might have 
been obtained, if the colonies of which sections were to be cut 
had been taken at random, instead of having been chosen with 
some regard to the condition of their polypides. 
I am unable to suggest any definite cause for the degenera- 
tion in most cases. A Protozoon, a species of Folliculina, 
is commonly found with the basal end of its tube embedded in 
the Lichenopora, its free end projecting from the surface of 
the colony. These organisms can often be recognised in the 
sections of the colonies, and in many cases they are found in 
degenerating specimens. It is quite possible that the Foll1- 
culina may in these cases be the cause of degeneration ; but 
it is equally possible that it is the effect, and that the Protozoa 
settle down in parts of the colony which have lost their zocecia. 
They are found, not uncommonly, in parts of the colony in 
which their presence does not seem to have had any effect on 
the adjacent zocecia. 
Degeneration may start at any stage of the embryonic de- 
velopment. I have observed it most commonly in colonies in 
which the embryo had developed up to the “ suspensor stage ; ” 
but I have also found it commencing at later stages, as, for 
instance, at the beginning of embryonic fission, or even later. 
In describing the development of the structures found within 
the ovicell of Lichenopora verrucaria, it is desirable to 
keep the account of the first brood of larve entirely separate 
from that of later broods. The appearance of an ovicell con- 
taining larve belonging to the first brood has already been 
considered (fig. 11); and this is the condition which is usually 
found in colonies which have a diameter of 1 mm. or there- 
abouts. The origin of all these complicated struc- 
tures is to be looked for in colonies which consist 
of only three or four zoecia. 
For descriptive purposes it will be convenient to classify 
the embryos in a certain number of stages; and it will be 
seen that the form of the entire colony has a distinct relation 
to these stages, although wide variations occur in the period 
at which any particular stage of development is passed through. 
