136 SIDNEY F. HARMER. 
made on the next page for L. grignonensis, Busk. Waters 
unfortunately does not figure any of these specimens with a 
depressed centre and without cancelli; but these features 
certainly point to the conclusion that no ovicell is present. 
Waters’ statements are in strong contrast with my own results 
on L, verrucaria, in which the ovicell is potentially present, 
as shown by the alterations in the fertile zoccium in most 
colonies which consist of no more than four or five, or even 
three zocecia ; and it is actually present and recognisable from 
the outside in all colonies which have reached a slightly later 
Stage. 
It would no doubt be going too far to assume that what is 
true for L. verrucaria necessarily holds for other species of 
Lichenopora. I am not at present able to make an inde- 
pendent examination of other species ; and although the ovicells 
of some of them have been described by Waters (24, 26) and 
others, the descriptions refer almost entirely to the external 
form, and I can find practically no points of comparison which 
assist in forming a conclusion as to the morphology of the 
ovicell. Waters in one place (25, p. 277) alludes to a feature 
which may have some relation with some of the phenomena 
described above in L. verrucaria. Speaking of Hornera 
(“Idmonea”’) fissurata, Busk, Waters states that he could 
not discover any opening to the ovicell, but that one of the 
lateral zocecia was much larger than the others, and it appeared 
that this change was “connected with the functions of the 
ovicell.” In each of the ovicells subsequently examined by 
Mr. Kirkpatrick one or two zowcia in proximity to the ovicell 
were enlarged and altered in direction. It would be interest- 
ing to know whether the enlarged zocecium in this case had 
any resemblance to the fertile zocecium in L. verrucaria. 
The ovicell seems to be practically identical in all species of 
Lichenopora in which it has been described. It always 
forms an inflated area between the upstanding zocecia, and it 
is usually known to occupy the centre of the colony. In some 
species it is extremely difficult to recognise the ovicell at all. 
I cannot help suspecting that the ovicell normally develops at 
