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ON THE DEVELOPMENT OF LICHENOPORA VERRUCARIA. 137 
an early stage in most, if not all, of the species of Licheno- 
pora, and that the presence of cancelli between the rows of 
zocecia is an indication that the ovicell is developing, even 
though no other evidence is obtained of its presence. 
There are, however, other genera of Cyclostomata in which 
the ovicell is of a simpler character than in Lichenopora. 
Thus in Discotubigera lineata, MacG., as figured by 
Waters (26, pl. xv, fig. 5), the ovicell is a lobed structure 
which extends over a comparatively small area of the discoidal 
colony near its margin. It opens by a single aperture to the 
exterior. A similar form of ovicell occurs in the genus Diasto- 
pora. It appears to me that these ovicells resemble those of 
Liche nopora reduced to simpler terms, and they are, perhaps, 
to some extent intermediate between the two genera which I 
have specially studied. Taking into account the origin of the 
ovicell in Lichenopora from an ordinary zocecium, the fact 
that the ovicell of Crisia is demonstrably a modified zocecium, 
and the existence of intermediates between these two extremes, 
I venture to suggest that that of Lichenopora is also to be 
regarded as formed by the modification of a zocecium. The 
fertile zocecium is prevented by the position which it occupies 
near the centre of the full-grown colony from expanding at its 
basal end. Expansion of some kind is necessary, in order to 
provide room for the swarm of secondary embryos ; andif there 
is anything in this suggestion, it may be supposed that the 
significance of the process is that the fertile zocecium has 
become swollen at its upper end. Instead of growing out as 
a free appendage of the colony, the swollen part has applied 
itself to the upper surfaces of the zocecia, and has filled up all 
the spaces intervening between the zocecia. The result is the 
same as if the ovicell had become amceboid, its pseudopodia 
extending between the zocecia, embracing them, and anasto- 
mosing on the further side of each. In the cases where two 
or more zocecia become fertile, the ovicell may be regarded as 
being composed of as many original zoovcia. 
The actual formation of the ovicell, by the formation of the 
alveoli and their subsequent fusion with one another, is of 
