106 SIDNEY F. HARMER. 
for the egg of Crisia, and the correspondence is even closer 
if we take the largest Lichenopora egg (16) of which I have 
a record. 
In a single case I have found an egg-like cell, 9°6 u in dia- 
meter, at the growing margin of acolony. This cell corresponds 
closely in appearance and position with the eggs which I have 
described in the growing-points of Crisia. I do not, however, 
feel by any means sure that this condition really represents a 
normal phase of the development. Some of my other prepara- 
tions suggest that the egg is more probably differentiated in 
situ from the outer layer of a young polypide bud. Moreover 
the brown body with which the developing embryo is associ- 
ated implies the loss of a polypide in the fertile zocecium. One 
might therefore expect, a priori, that the egg would make its 
appearance in a bud formed to replace a pre-existing polypide, 
and not in a part of the growing edge where no polypides have 
yet become mature. 
I have found cells which I regard as eggs in thirty-eight 
colonies. In. most cases I have been unable to detect more 
than a single egg in a colony, although in some cases two or 
even three eggs may occur in a single zoecium. The egg- 
bearing zocecilum is commonly 2? or z®, but in several colonies 
the egg occurred in a younger zocecium. In one or two of the 
latter cases either z? or z> was already preoccupied with an 
embryo of its own. ‘The observations I have noted down with 
regard to the occurrence of these cells point strongly in the 
direction of their being eggs. They do not occur promiscuously 
in all the zocecia. Should a colony have been successful in 
developing an embryo no further trace is ordinarily seen of eggs. 
In young colonies which have no embryo these cells are of 
common occurrence, and in very young colonies they are found 
in just those zoccia which might be expected to produce them. 
At the same time the results are not perfectly consistent, and I 
can best interpret them by assuming that there is considerable 
variation with regard to the first origin of the eggs. This 
appears to me to be particularly the case with young colonies 
in which the development has not been quite normal, whether 
